BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Anna Balci (Charles University) DTSTART:20240103T080000Z DTEND:20240103T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/1 DESCRIPTION:Title: Numerical approximation of variational problems with general and orthotrop ic growth\nby Anna Balci (Charles University) as part of Modelling of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Christoph Allolio (Charles University) DTSTART:20240110T080000Z DTEND:20240110T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/2 DESCRIPTION:Title: Modeling Biomembranes and Organelles: Consequences of Molecular Specificit y\nby Christoph Allolio (Charles University) as part of Modelling of m aterials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/2/ END:VEVENT BEGIN:VEVENT SUMMARY:Petr Šácha (Charles University) DTSTART:20240221T080000Z DTEND:20240221T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/3 DESCRIPTION:Title: Numerical experiments and climate model development efforts in the Gravity wave research group at KFA MFF UK\nby Petr Šácha (Charles Universit y) as part of Modelling of materials - theory\, model reduction and effici ent numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Jan Blechta (Charles University) DTSTART:20240228T080000Z DTEND:20240228T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/4 DESCRIPTION:Title: Divergence-preserving methods for incompressible flow\nby Jan Blechta (Charles University) as part of Modelling of materials - theory\, model re duction and efficient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/4/ END:VEVENT BEGIN:VEVENT SUMMARY:Alena Jarolímová (Charles University) DTSTART:20240306T080000Z DTEND:20240306T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/5 DESCRIPTION:Title: Determination of Navier's slip parameter and the inflow velocity using var iational data assimilation\nby Alena Jarolímová (Charles University) as part of Modelling of materials - theory\, model reduction and efficien t numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/5/ END:VEVENT BEGIN:VEVENT SUMMARY:Martin Čížek (Charles University) DTSTART:20240313T080000Z DTEND:20240313T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/6 DESCRIPTION:Title: Equations behind inelastic low-energy electron collisions with small molec ules\nby Martin Čížek (Charles University) as part of Modelling of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/6/ END:VEVENT BEGIN:VEVENT SUMMARY:Ondřej Souček (Charles University) DTSTART:20240320T080000Z DTEND:20240320T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/7 DESCRIPTION:Title: Variations in plume activity unveiling the dynamics of water-filled faults on Enceladus\nby Ondřej Souček (Charles University) as part of Mode lling of materials - theory\, model reduction and efficient numerical meth ods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/7/ END:VEVENT BEGIN:VEVENT SUMMARY:Jakub Fara (Charles University) DTSTART:20240327T080000Z DTEND:20240327T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/8 DESCRIPTION:Title: Beyond the edge of the ALE method: Simulation of Rebound\nby Jakub Far a (Charles University) as part of Modelling of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\ n LOCATION:https://researchseminars.org/talk/MathMAC/8/ END:VEVENT BEGIN:VEVENT SUMMARY:Alexander Wilkie (Charles University) DTSTART:20240403T070000Z DTEND:20240403T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/9 DESCRIPTION:Title: Realistic appearance modelling for movie VFX and 3D print applications \nby Alexander Wilkie (Charles University) as part of Modelling of materia ls - theory\, model reduction and efficient numerical methods (UNCE MathMA C)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/9/ END:VEVENT BEGIN:VEVENT SUMMARY:Alex Kaltenbach (TU Berlin) DTSTART:20240410T070000Z DTEND:20240410T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/10 DESCRIPTION:Title: Aposteriori error control for variational problems via convex duality\, e xplicit flux reconstruction\, and applications\nby Alex Kaltenbach (TU Berlin) as part of Modelling of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/10/ END:VEVENT BEGIN:VEVENT SUMMARY:Erin Carson (Charles University) DTSTART:20240424T070000Z DTEND:20240424T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/11 DESCRIPTION:Title: Balancing Inexactness in Matrix Computations\nby Erin Carson (Charles University) as part of Modelling of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\n\nAbstract\nOn supercomp uters that exist today\, achieving even close to the peak performance is i ncredibly difficult if not impossible for many applications. Techniques de signed to improve the performance of matrix computations- making computati ons less expensive by reorganizing an algorithm\, making intentional appro ximations\, and using lower precision- all introduce what we can generally call “inexactness”. The questions to ask are then:\n1. With all these various sources of inexactness involved\, does a given algorithm still ge t close enough to the right answer?\n2. Given a user constraint on require d accuracy\, how can we best exploit and balance different types of inexac tness to improve performance?\nStudying the combination of different sourc es of inexactness can thus reveal not only limitations\, but also new oppo rtunities for developing algorithms for matrix computations that are both fast and provably accurate. We present few recent results toward this goal \, involving mixed precision randomized decompositions and mixed precision sparse approximate inverse preconditioners.\n LOCATION:https://researchseminars.org/talk/MathMAC/11/ END:VEVENT BEGIN:VEVENT SUMMARY:Jan Vybíral (Czech Technical University\, Faculty of Nuclear Scie nces and Physical Engineering) DTSTART:20240417T070000Z DTEND:20240417T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/12 DESCRIPTION:Title: Lower bounds in numerical mathematics\nby Jan Vybíral (Czech Technic al University\, Faculty of Nuclear Sciences and Physical Engineering) as p art of Modelling of materials - theory\, model reduction and efficient num erical methods (UNCE MathMAC)\n\n\nAbstract\nIn the analysis of algorithms \, there is usually a big difference between upper and lower bounds. Upper bounds (on the running time\, memory used or necessary input information) is usually achieved by a construction of an efficient algorithm. On the o ther hand\, lower bounds show that the construction of better and better a lgorithms has some natural limits. We study lower bounds on the amount of input information needed for algorithms in numerical analysis. The problem s discussed include numerical integration\, signal processing\, and discre te geometry. Naturally\, we encounter connections to functional analysis\, probability\, and combinatorics.\n LOCATION:https://researchseminars.org/talk/MathMAC/12/ END:VEVENT BEGIN:VEVENT SUMMARY:Carola Bibiane Schönlieb (Department of Applied Mathematics and T heoretical Physics\, University of Cambridge) DTSTART:20240906T120000Z DTEND:20240906T130000Z DTSTAMP:20260422T090347Z UID:MathMAC/13 DESCRIPTION:Title: Mathematical imaging: From geometric PDEs and variational modelling to de ep learning for images\nby Carola Bibiane Schönlieb (Department of Ap plied Mathematics and Theoretical Physics\, University of Cambridge) as pa rt of Modelling of materials - theory\, model reduction and efficient nume rical methods (UNCE MathMAC)\n\n\nAbstract\nImages are a rich source of be autiful mathematical formalism and analysis. Associated mathematical probl ems arise in functional and non-smooth analysis\, the theory and numerical analysis of nonlinear partial differential equations\, inverse problems\, harmonic\, stochastic and statistical analysis\, and optimisation. In thi s talk we will learn about some of these mathematical problems\, about var iational models and PDEs for image analysis and inverse imaging problems a s well as recent advances where such mathematical models are complemented and replaced by deep neural networks. The talk is furnished with applicati ons to art restoration\, forest conservation and cancer research.\n LOCATION:https://researchseminars.org/talk/MathMAC/13/ END:VEVENT BEGIN:VEVENT SUMMARY:Vít Průša (Mathematical Institute\, Faculty of Mathematics and Physics\, Charles University) DTSTART:20241002T070000Z DTEND:20241002T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/14 DESCRIPTION:Title: Negative thoughts on negative mass\nby Vít Průša (Mathematical Ins titute\, Faculty of Mathematics and Physics\, Charles University) as part of Modelling of materials - theory\, model reduction and efficient numeric al methods (UNCE MathMAC)\n\n\nAbstract\nThe concept of effective mass is frequently used for simplification of complex models. It i claimed that in the case of wave transmission analysis of some metamaterials the correspo nding effective mass can be frequency dependent\, negative and it may not even be a scalar quantity. These findings have even led some authors to su ggest that Newton's second law needs to be modified within the context of classical continuum mechanics. While there is nothing wrong with the mathe matical procedures used to reach these conclusions\, the accompanying phys ical interpretation thereof is absurd. We show that the puzzling concept o f negative mass can be easily eliminated provided that we model the corres ponding metamaterials using an effective constitutive relation. The effect ive constitutive relation is a rate-type constitutive relation\, and the s imple models we study give a clue how to design a non-trivial effective ra te-type constitutive relation that is conservative\, that is\, possessing an associated conserved energy depending on the force/stress and its time derivatives. In short\, the rate-type constitutive relations obtained in o ur study might be seen as a revival of hypoelastic materials.\n LOCATION:https://researchseminars.org/talk/MathMAC/14/ END:VEVENT BEGIN:VEVENT SUMMARY:Michal Outrata DTSTART:20241009T070000Z DTEND:20241009T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/15 DESCRIPTION:Title: Domain Truncation\, Absorbing Boundary Conditions\, Schur Complements\, a nd Padé Approximation\nby Michal Outrata as part of Modelling of mate rials - theory\, model reduction and efficient numerical methods (UNCE Mat hMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/15/ END:VEVENT BEGIN:VEVENT SUMMARY:Michal Bathory DTSTART:20241016T070000Z DTEND:20241016T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/16 DESCRIPTION:Title: Relative energy inequality for viscoelastic fluid models with application s to stability\nby Michal Bathory as part of Modelling of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\ nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/16/ END:VEVENT BEGIN:VEVENT SUMMARY:Umberto Zerbinati DTSTART:20241023T070000Z DTEND:20241023T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/17 DESCRIPTION:Title: A Kinetic Framework for Fluids with Partial Ordering\nby Umberto Zerb inati as part of Modelling of materials - theory\, model reduction and eff icient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/17/ END:VEVENT BEGIN:VEVENT SUMMARY:Radomír Chabiniok DTSTART:20241030T080000Z DTEND:20241030T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/18 DESCRIPTION:Title: Biomechanical Modeling for Congenital Heart Diseases\nby Radomír Cha biniok as part of Modelling of materials - theory\, model reduction and ef ficient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/18/ END:VEVENT BEGIN:VEVENT SUMMARY:Michal Pavelka DTSTART:20241106T080000Z DTEND:20241106T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/19 DESCRIPTION:Title: Modelling superfluid helium\nby Michal Pavelka as part of Modelling o f materials - theory\, model reduction and efficient numerical methods (UN CE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/19/ END:VEVENT BEGIN:VEVENT SUMMARY:Petr Pelech\, Läetitia Lebec DTSTART:20241113T080000Z DTEND:20241113T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/20 DESCRIPTION:Title: Semester seminar of junior researchers\nby Petr Pelech\, Läetitia Le bec as part of Modelling of materials - theory\, model reduction and effic ient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/20/ END:VEVENT BEGIN:VEVENT SUMMARY:Kim Myyryläinen\, Anna Balci DTSTART:20241120T080000Z DTEND:20241120T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/21 DESCRIPTION:Title: Semester seminar of junior researchers\nby Kim Myyryläinen\, Anna Ba lci as part of Modelling of materials - theory\, model reduction and effic ient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/21/ END:VEVENT BEGIN:VEVENT SUMMARY:Liam Burke\, Yuxin Ma DTSTART:20241127T080000Z DTEND:20241127T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/22 DESCRIPTION:Title: Semester seminar of junior researchers\nby Liam Burke\, Yuxin Ma as p art of Modelling of materials - theory\, model reduction and efficient num erical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/22/ END:VEVENT BEGIN:VEVENT SUMMARY:Petr Šácha\, Lenka Slavíková DTSTART:20241204T080000Z DTEND:20241204T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/23 DESCRIPTION:Title: Semester seminar of junior researchers\nby Petr Šácha\, Lenka Slav íková as part of Modelling of materials - theory\, model reduction and e fficient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/23/ END:VEVENT BEGIN:VEVENT SUMMARY:Jan Blechta\, Michal Outrata DTSTART:20241211T080000Z DTEND:20241211T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/24 DESCRIPTION:Title: Semester seminar of junior researchers\nby Jan Blechta\, Michal Outra ta as part of Modelling of materials - theory\, model reduction and effici ent numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/24/ END:VEVENT BEGIN:VEVENT SUMMARY:Ondřej Chrenko\, Vojtěch Patočka DTSTART:20241218T080000Z DTEND:20241218T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/25 DESCRIPTION:Title: Semester seminar of junior researchers\nby Ondřej Chrenko\, Vojtěch Patočka as part of Modelling of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/25/ END:VEVENT BEGIN:VEVENT SUMMARY:Alexei Gazca Orozco DTSTART:20250219T080000Z DTEND:20250219T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/26 DESCRIPTION:Title: A priori and a posteriori estimates for vectorial problems via convex dua lity\nby Alexei Gazca Orozco as part of Modelling of materials - theor y\, model reduction and efficient numerical methods (UNCE MathMAC)\n\n\nAb stract\nBy exploiting remarkable properties of the Crouzeix-Raviart and Ra viart-Thomas finite elements\, numerous works in recent years have been ab le to employ convex duality theory to derive error estimates for a diverse set of problems\, including total variation minimisation\, the p-Laplacia n\, the obstacle problem\, elastoplastic torsion\, among others. However\, virtually all of the available results have been developed for scalar pro blems with homogeneous Dirichlet boundary conditions. This work extends th e existing results in three directions\, taking the incompressible Stokes and linear elasticity systems as prototypical examples: it considers vecto rial as opposed to just scalar problems\, it includes non-homogeneous mixe d boundary conditions\, as well as loads in the dual of the energy space.\ n LOCATION:https://researchseminars.org/talk/MathMAC/26/ END:VEVENT BEGIN:VEVENT SUMMARY:Ondřej Kincl DTSTART:20250226T080000Z DTEND:20250226T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/27 DESCRIPTION:Title: Understanding Smoothed Particle Hydrodynamics\nby Ondřej Kincl as pa rt of Modelling of materials - theory\, model reduction and efficient nume rical methods (UNCE MathMAC)\n\n\nAbstract\nThis talk provides a beginner- friendly overview of weakly compressible Smoothed Particle Hydrodynamics ( SPH)\, a mesh-free method for solving the Navier-Stokes equations. I will explain fundamental concepts such as smoothing kernels\, the two-step appr oximation of spatial derivatives\, and symplectic integrators for time dis cretization. The benefits and limitations of SPH will be compared to mesh- based approaches like the Finite Element Method. Finally\, I will illustra te key ideas from the convergence analysis of Di Lisio et al.\, which reli es on the Wasserstein metric and offers valuable theoretical insight.\n LOCATION:https://researchseminars.org/talk/MathMAC/27/ END:VEVENT BEGIN:VEVENT SUMMARY:Marc Fehling DTSTART:20250305T080000Z DTEND:20250305T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/28 DESCRIPTION:Title: hp-adaptive finite element methods\nby Marc Fehling as part of Modell ing of materials - theory\, model reduction and efficient numerical method s (UNCE MathMAC)\n\n\nAbstract\nhp-adaptive finite element methods allow t o choose both the mesh size h and the polynomial degree p locally on every cell. Despite their excellent convergence properties\, these methods are not widely used\, likely due to the complexities involved in their impleme ntation. To facilitate their use\, we have recently introduced comprehensi ve support for hp-adaptive methods in the open-source library deal.II\, in cluding parallel computation capabilities for continuous Galerkin methods. \n\nIn this presentation\, we will explore the general idea behind hp-adap tive finite element methods\, address challenges encountered in their para llel implementation\, and showcase example applications developed using th e deal.II library. Particular attention will be given to the design of eff icient solvers for the resulting systems of equations.\n LOCATION:https://researchseminars.org/talk/MathMAC/28/ END:VEVENT BEGIN:VEVENT SUMMARY:Patrick E. Farrell (University of Oxford) DTSTART:20250312T150000Z DTEND:20250312T160000Z DTSTAMP:20260422T090347Z UID:MathMAC/29 DESCRIPTION:Title: Predicting the future by solving equations\nby Patrick E. Farrell (Un iversity of Oxford) as part of Modelling of materials - theory\, model red uction and efficient numerical methods (UNCE MathMAC)\n\n\nAbstract\nHuman s have sought to predict the future for as long as we have existed. One of the key ideas\nof the scientific revolution was that we can predict the f uture of physical systems by writing\ndown the laws of physics as differen tial equations and solving them. Our capacity to do this\nhas recently inc reased dramatically due to better computers\, and better algorithms. This\ ntechnology has quietly revolutionised industrial civilisation in countles s ways\, from\npredicting the weather a week in advance\, to designing spa ce planes without wind tunnels\, and\nto understanding the gravitational w aves detected by LIGO. In this lecture I will review this\nsubject\, discu ss some of my own contributions\, and mention some important open problems in\nthe field.\n LOCATION:https://researchseminars.org/talk/MathMAC/29/ END:VEVENT BEGIN:VEVENT SUMMARY:Jiří Falta DTSTART:20250319T080000Z DTEND:20250319T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/30 DESCRIPTION:Title: Mathematical Modeling of Process-Structure Interaction in Machining\n by Jiří Falta as part of Modelling of materials - theory\, model reducti on and efficient numerical methods (UNCE MathMAC)\n\n\nAbstract\nMachining operations involve complex interactions between the cutting process and t he structural dynamics of the machine-tool-workpiece system. The presentat ion provides an overview of mathematical models describing these interacti ons\, focusing on dynamics\, vibrations\, and surface formation.\nThis ove rview presentation begins with a general introduction to the machining wor kflow from CAD-CAM to CNC\, linking it to structural behavior and surface accuracy. This is followed by an analysis of representative machining proc esses—turning\, milling\, and grinding\, showing different physical effe cts and their corresponding mathematical formulations. Finally\, an overvi ew of simulation software development for milling will be presented\, demo nstrating its role in machining process optimization.\n LOCATION:https://researchseminars.org/talk/MathMAC/30/ END:VEVENT BEGIN:VEVENT SUMMARY:Malte Kampschulte DTSTART:20250326T080000Z DTEND:20250326T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/31 DESCRIPTION:Title: A variational view of nonlinear and linear viscoelastodynamics\nby Ma lte Kampschulte as part of Modelling of materials - theory\, model reducti on and efficient numerical methods (UNCE MathMAC)\n\n\nAbstract\nThe aim o f this talk is to present a comprehensive variational\nview of viscoelasto dynamics. First we will consider the modelling of the\nproblem from an ene rgetical perspective. Then we will see how existence\nof solutions to stat ic\, quasistatic and dynamic problems can all be\nderived by consecutive v ariational methods following that energetical\nstructure. Finally we study the convergence to the linearization\nemploying the variational concept o f $\\Gamma$-convergence. This is based\non joint work with B.Benešová an d M.Kružík.\n LOCATION:https://researchseminars.org/talk/MathMAC/31/ END:VEVENT BEGIN:VEVENT SUMMARY:Vít Průša DTSTART:20250402T070000Z DTEND:20250402T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/32 DESCRIPTION:Title: Effective models for mechanical response of metamaterials\nby Vít Pr ůša as part of Modelling of materials - theory\, model reduction and eff icient numerical methods (UNCE MathMAC)\n\n\nAbstract\nWe propose a thermo dynamically based approach for constructing effective rate-type constituti ve relations describing finite deformations of metamaterials. The effectiv e constitutive relations are formulated as second-order in time rate-type Eulerian constitutive relations between only the Cauchy stress tensor\, th e Hencky strain tensor and objective time derivatives thereof. In particul ar\, there is no need to introduce additional quantities or concepts such as ``micro-level deformation''\,``micromorphic continua''\, or elastic sol ids with frequency dependent material properties.\n\nMoreover\, the linear isation of the proposed fully nonlinear (finite deformations) constitutive relations leads\, in Fourier/frequency space\, to the same constitutive r elations as those commonly used in theories based on the concepts of frequ ency dependent density and/or stiffness. From this perspective the propose d constitutive relations reproduce the behaviour predicted by the frequenc y dependent density and/or stiffness models\, but yet they work with const ant---that is motion independent---material properties. This is clearly mo re convenient from the physical point of view. Furthermore\, the linearise d version of the proposed constitutive relations leads to the governing pa rtial differential equations that are particularly simple both in Fourier space as well as in physical space.\n\nFinally\, we argue that the propose d fully nonlinear (finite deformations) second-order in time rate-type con stitutive relations do not fall into traditional classes of models for ela stic solids (hyperelastic solids/Green elastic solids\, first-order in tim e hypoelastic solids)\, and that the proposed constitutive relations embod y a new class of constitutive relations characterising elastic solids.\n LOCATION:https://researchseminars.org/talk/MathMAC/32/ END:VEVENT BEGIN:VEVENT SUMMARY:Jaroslav Hron DTSTART:20250409T070000Z DTEND:20250409T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/33 DESCRIPTION:Title: Numerical investigation of blood flows with slip boundary conditions\ nby Jaroslav Hron as part of Modelling of materials - theory\, model reduc tion and efficient numerical methods (UNCE MathMAC)\n\n\nAbstract\nMost st udies of patient-specific blood flow models prescribe a no-slip boundary c ondition at the walls. Although its implementation is straightforward\, it s validity at the blood-vessel wall interface is questionable. It has been suggested in (Nubar\, 1971) for example\, that a slip boundary condition can be considered for blood flow in certain situations. We will discuss so me effects of prescribing the Navier-type slip boundary condition\, which assumes a linear proportionality between the tangential part of the wall v elocity and the shear stress using an additional parameter. Such condition can be extended to full fluid-structure interaction problem. Finally\, gi ven some measured flow data\, for example modern 4D-PC MRI image\, we use variational data assimilation approach to estimate the Navier's slip param eter on the vessel wall for real data.\n LOCATION:https://researchseminars.org/talk/MathMAC/33/ END:VEVENT BEGIN:VEVENT SUMMARY:Milan Šimek\, Zdeněk Bonaventura DTSTART:20250416T070000Z DTEND:20250416T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/34 DESCRIPTION:Title: Non-Equilibrium Plasma–Water Interactions: Experimental and Theoretical Approaches\nby Milan Šimek\, Zdeněk Bonaventura as part of Modellin g of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\n\nAbstract\nNitrogen is essential for industry and agric ulture\, but converting abundant atmospheric nitrogen into reactive forms requires signifi cant energy. Intermittent renewable energy sources (e.g.\ , wind and solar) can power non-equilibrium plasma sources\, which effi ci ently generate nitrogen- and oxygen-based reactive species (RONS). One com mon way to produce such reactive plasmas is through streamer–spark disch arges\, initiated by strong electric fi elds from nanosecond/microsecond p ulsed high-voltage power sources. These discharges can operate in direct c ontact with the liquid surface\, thus creating and storing RONS in so-call ed plasma-activated water (PAW). In the agri-food sector\, PAW offers a wi de range of possible applications (e.g. suppression of bacterial activity or nutrient solution for plants in hydroponic systems).\n\nThis seminar ai ms to\, in two parts\, provide an overview of experimental and numerical m odeling approaches\, both aimed at optimizing RONS generation in non-equil ibrium plasmas and enhancing their incorporation into plasma-activated wat er.\n LOCATION:https://researchseminars.org/talk/MathMAC/34/ END:VEVENT BEGIN:VEVENT SUMMARY:Karel Tůma DTSTART:20250423T070000Z DTEND:20250423T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/35 DESCRIPTION:Title: Multiwell model of phase separation: Arbitrarily strong total-spreading c ase\nby Karel Tůma as part of Modelling of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\n\nAbstract\nI n this work\, we revisit a multi-well phase separation model in the contex t of β–ω transformations in titanium alloys. We propose a new formulat ion by modifying the algebraic structure of the interfacial free energy. T his adjustment relaxes the standard coercivity constraint on surface tensi ons in total-spreading regimes and\, importantly\, prevents the formation of mixed ω–ω states—configurations that are crystallographically imp ossible. We demonstrate the effectiveness of the proposed model through si mplified simulations and outline a path toward more realistic three-dimens ional modeling of β–ω phase transitions in titanium alloys.\n LOCATION:https://researchseminars.org/talk/MathMAC/35/ END:VEVENT BEGIN:VEVENT SUMMARY:Patrick Farrell DTSTART:20250514T070000Z DTEND:20250514T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/36 DESCRIPTION:Title: Discretising the Stokes-Onsager-Stefan-Maxwell equations of multicomponen t flow\nby Patrick Farrell as part of Modelling of materials - theory\ , model reduction and efficient numerical methods (UNCE MathMAC)\n\n\nAbst ract\nMulticomponent fluids are mixtures of distinct chemical species (i.e . components) that interact through complex physical processes such as cro ss-diffusion and chemical reactions. Additional physical phenomena often m ust be accounted for when modelling these fluids\; examples include moment um transport\, thermal effects\, and (for charged species) electrical effe cts.\n\nDespite the ubiquity of chemical mixtures in nature and engineerin g\, multicomponent fluids have received almost no attention from the finit e element community\, with many important applications remaining out of re ach from numerical methods currently available in the literature.\n\nIn th is talk\, we present a novel class of high-order finite element methods fo r simulating cross-diffusion and momentum transport (i.e. convection) in m ulticomponent fluids modelled with the Stokes-Onsager-Stefan-Maxwell equat ions. Our model can also incorporate local electroneutrality when the spec ies carry electrical charge\, making the numerical methods particularly de sirable for simulating liquid electrolytes in electrochemical applications . We discuss challenges that arise when discretising the partial different ial equations of multicomponent flow\, as well as some salient theoretical properties of our numerical schemes.\n\nFinally\, we present numerical si mulations involving (i) the microfluidic non-ideal mixing of hydrocarbons and (ii) the transient evolution of a lithium-ion battery electrolyte in a Hull cell electrode.\n LOCATION:https://researchseminars.org/talk/MathMAC/36/ END:VEVENT BEGIN:VEVENT SUMMARY:Jakub Cach DTSTART:20250521T070000Z DTEND:20250521T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/37 DESCRIPTION:Title: Traction profiles of the Turek benchmark and their relation to bifurcatio ns for Navier Stokes fluids\nby Jakub Cach as part of Modelling of mat erials - theory\, model reduction and efficient numerical methods (UNCE Ma thMAC)\n\n\nAbstract\nWe present a consistent numerical study on the stabi lity of the Navier-Stokes fluid in the confined flow around a cylinder. We performed the study within the Turek benchmark for Reynolds numbers up to 1000. The key outcome is that changes in the nature of flow regimes are d riven by the upstream dynamics of the cylinder obstacle rather than by the downstream effect in the vortex wake. It turns out that the most sensitiv e indicator is the pointwise traction profile on the cylinder boundary. An other observation is in the case of laminar vortex shedding\, where the mu ltiple steady solutions differ from the global-in-time attractor\, which a ppears to be unique and robust across a large range of Reynolds numbers. A s an auxiliary contribution\, we also discuss a weak (variational) formula tion for traction computation\, which offers practical advantages.\n LOCATION:https://researchseminars.org/talk/MathMAC/37/ END:VEVENT BEGIN:VEVENT SUMMARY:Artem Ryabov DTSTART:20251001T070000Z DTEND:20251001T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/38 DESCRIPTION:Title: Solitary cluster waves in driven dense colloids\nby Artem Ryabov as p art of Modelling of materials - theory\, model reduction and efficient num erical methods (UNCE MathMAC)\n\n\nAbstract\nWe will discuss the static an d dynamic states of hard spheres confined in one-dimensional periodic pote ntials at high particle densities. Such systems can reside in a mechanical equilibrium or in running states characterized by soliton-mediated transp ort [1-3]. For weak external driving\, these solitary cluster waves emerge in narrow intervals of specific particle sizes. The minimal number of par ticles needed to trigger the soliton propagation follows from conditions o f mechanical equilibrium and can be determined by a geometric principle of minimum residual free space. We further address the number of propagating solitons\, their mutual interactions\, the influence of external forcing\ , and present experimental evidence for such solitary excitations in drive n colloidal systems [4].\n\n[1] AP Antonov\, A Ryabov\, P Maass\, Phys. Re v. Lett. 129\, 080601 (2022)\n[2] AP Antonov\, A Ryabov\, P Maass\, Chaos\ , Solitons & Fractals 185\, 115079 (2024)\n[3] AP Antonov\, A Vonhusen\, A Ryabov\, P Maass\, Nonlinear Dyn. (2025) doi: 10.1007/s11071-025-11626-x\ n[4] E Cereceda-Lopez\, et al.\, Nat. Commun. 14\, 6448 (2023)\n LOCATION:https://researchseminars.org/talk/MathMAC/38/ END:VEVENT BEGIN:VEVENT SUMMARY:Aaron Baier-Reineo DTSTART:20251008T070000Z DTEND:20251008T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/39 DESCRIPTION:Title: Finite element methods for electroneutral multicomponent convection-diffu sion\nby Aaron Baier-Reineo as part of Modelling of materials - theory \, model reduction and efficient numerical methods (UNCE MathMAC)\n\n\nAbs tract\nMulticomponent fluids are those consisting of multiple chemical spe cies. Complex physical processes occur within these fluids\; examples incl ude cross-diffusion\, chemical reactions\, momentum transport\, thermality and (for charged species) electrical effects. Despite their ubiquity in s cience and engineering\, multicomponent fluids have received limited atten tion from the finite element community\, and many important applications r emain out of reach from current numerical methods. In this talk\, we prese nt novel high-order finite element methods for multicomponent cross-diffus ion and momentum transport. Our model can also incorporate local electrone utrality when the species carry electrical charge\, making the methods par ticularly desirable for simulating liquid electrolytes in electrochemical applications. We discuss challenges that arise when discretising the gover ning partial differential equations\, as well as some salient theoretical properties of the numerical schemes. Finally\, we present numerical simula tions involving (i) the microfluidic non-ideal mixing of hydrocarbons and (ii) a lithium-ion battery electrolyte in a Hull cell electrode.\n LOCATION:https://researchseminars.org/talk/MathMAC/39/ END:VEVENT BEGIN:VEVENT SUMMARY:Josef Málek DTSTART:20251015T070000Z DTEND:20251015T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/40 DESCRIPTION:Title: On non-isothermal flows of dilute incompressible polymeric fluids\nby Josef Málek as part of Modelling of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\n\nAbstract\nIn the firs t part of the talk\, we show that thermodynamically consistent models for non-isothermal flows of such fluids can be derived in a very elementary ma nner. Our approach is based on identifying the energy storage mechanisms a nd entropy production mechanisms in the fluid of interest\, which in turn leads to explicit formulae for the Cauchy stress tensor and for all the fl uxes involved. Having identified these mechanisms\, we first derive the go verning system of nonlinear partial differerential equations coupling the unsteady incompressible temperature-dependent Navier–Stokes equations wi th a temperature-dependent generalization of the classical Fokker–Planck equation and an evolution equation for the internal energy. In the second - main part - of the talk\, we show that sequences of smooth solutions to the initial–boundary-value problem\, which satisfy the underlying energ y/entropy estimates (and their consequences in connection with the governi ng system of PDEs)\, converge to weak solutions that satisfy a renormalize d entropy inequality. The talk is based on joint results with Miroslav Bul íček\, Mark Dostalík\, Vít Průša and Endré Süli.\n LOCATION:https://researchseminars.org/talk/MathMAC/40/ END:VEVENT BEGIN:VEVENT SUMMARY:Simone Marras DTSTART:20251022T070000Z DTEND:20251022T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/41 DESCRIPTION:Title: Noise\, ripples\, and other oscillations in numerical weather > predictio n. A brief survey of how to treat them.\nby Simone Marras as part of M odelling of materials - theory\, model reduction and efficient numerical m ethods (UNCE MathMAC)\n\n\nAbstract\nThe advent of inexpensive massively p arallel computers in the past fifteen years has revolutionized the way num erical weather prediction\, climate and ocean modeling are handled today. In this talk\, I will describe how this revolution happened\, the reasons that drove it\, and what challenges are still to be fully addressed and re solved as exascale computing approaches.\n\nI will concentrate on the use of high-order continuous and discontinuous spectral elements (SEM) as they are proving their mettle for solving the Navier-Stokes equations to model atmospheric motion. Because of the high susceptibility of SEM to Gibbs os cillations in the solution to non-linear problems\, special attention will be given to understanding how their stabilization is still an active topi c of research and how we are contributing towards its solution.\n LOCATION:https://researchseminars.org/talk/MathMAC/41/ END:VEVENT BEGIN:VEVENT SUMMARY:Christoph Allolio DTSTART:20251105T080000Z DTEND:20251105T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/42 DESCRIPTION:Title: Molecular Grammar of Microtubule-Wetting Biomolecular Condensates\nby Christoph Allolio as part of Modelling of materials - theory\, model redu ction and efficient numerical methods (UNCE MathMAC)\n\n\nAbstract\nBiomol ecular condensates are a recently discovered new ordering principle of the cell. They consist of partially disordered proteins\, which undergo liqui d-liquid phase separation inside the cytosol\, turning the cell into a mul tiphase mixture. Microtubuli are the backbone of the cytoskeleton in the s ense that they are the entities inside the cell that is able to generate t he largest mechanical force.\n\nMicrotubule condensate interactions are fu ndamental for cell division\, vesicle transport and cellular locomotion. A ccordingly\, they represent a large number of attractive drug targets. Due to the size of microtubuli and the slow timescale of condensate structura l relaxation\, there has not been a systematic investigation at the molecu lar level as to what binding patterns (molecular grammar) enable condensat e binding to microtubuli. We provide a protocol that is able to predict wh ether any given disordered protein sequence will bind to microtubuli. This protocol is suitable for high-throughput screening. Our pattern analysis allows us to establish two categories of strongly interacting subsequences that enable binding to microtubuli: positively charged hydrophobic cluste rs and alternating charge sequences. Their overall optimal balance is anal yzed and preferential regions of interaction on microtubuli are identified and validated with known experimental results. Our results enable rapid p rototyping of proteins that target the microtubule surface\, i.e. they pre dict whether unstructured proteins will wet the microtubule interface.\n LOCATION:https://researchseminars.org/talk/MathMAC/42/ END:VEVENT BEGIN:VEVENT SUMMARY:Umberto Zerbinati DTSTART:20251112T080000Z DTEND:20251112T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/43 DESCRIPTION:Title: A Kinetic Interpretation of Thermochemical Restrictions of Continua\n by Umberto Zerbinati as part of Modelling of materials - theory\, model re duction and efficient numerical methods (UNCE MathMAC)\n\n\nAbstract\nIn t heir seminal work\, Rajagopal and Srinivasa established how the second law of thermodynamics\, expressed through the Clausius–Duhem inequality\, i mposes powerful restrictions on the constitutive equations of continua\, o ften allowing one to determine the constitutive relations of a material. T his talk explores a kinetic interpretation of such thermochemical restrict ions. The analysis of the entropy balance naturally yields a kinetic analo gue of the Clausius–Duhem inequality\, while the H-theorem provides a mi croscopic justification of the second law. In the hydrodynamic limit\, a C hapman–Enskog expansion demonstrates how the classical constitutive rela tions of continuum mechanics—such as the Euler equations and the ideal g as law—arise as zeroth-order approximations that maximize entropy produc tion. We hope that this kinetic perspective offers a new interpretation of the thermomechanical restrictions introduced by Rajagopal and collaborato rs\, clarifying their origin within the statistical description of particl e systems.\n LOCATION:https://researchseminars.org/talk/MathMAC/43/ END:VEVENT BEGIN:VEVENT SUMMARY:S. Leveque\, R. Khan\, Y. Ma DTSTART:20251119T080000Z DTEND:20251119T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/44 DESCRIPTION:Title: Semester seminar of junior researchers\nby S. Leveque\, R. Khan\, Y. Ma as part of Modelling of materials - theory\, model reduction and effici ent numerical methods (UNCE MathMAC)\n\n\nAbstract\nSantolo Leveque

\nAn Augmented Lagrangian preconditioner for the control of the Navi er–Stokes equations
\nOptimal control problems with PDEs as const raints arise very often in scientific and industrial applications. Due to the difficulties arising in their numerical solution\, researchers have pu t a great effort into devising robust solvers for this class of problems. An example of a highly challenging problem attracting significant attentio n is the distributed control of incompressible viscous fluid flow problems . In this case\, the physics is described by the incompressible Navier–S tokes equations. Since the PDEs given in the constraints are nonlinear\, i n order to obtain a solution of Navier–Stokes control problems one has t o iteratively solve linearizations of the problems until a prescribed tole rance on the non-linear residual is achieved. In this talk\, we present ef ficient and robust preconditioned iterative methods for the solution of th e stationary incompressible Navier–Stokes control problem\, when employi ng an inexact Newton linearization of the first-order optimality condition s. The iterative solver is based on an augmented Lagrangian preconditioner . By employing saddle-point theory\, we derive suitable approximations of the (1\,1)-block and the Schur complement. Numerical experiments show the effectiveness and robustness of our approach\, for a range of problem para meters.

\n\n\nRitesh Khan

\nAccelerating Dense Matrix Comput ations Using Hierarchical Matrices
\nDense matrices arise frequentl y across many areas\, such as PDEs\, inverse problems\, integral equations \, machine learning\, kernel methods\, etc. In many practical applications \, these dense matrices can be very large\, making matrix operations invol ving them quite challenging. For example\, the direct evaluation of the de nse matrix-vector product in the potential theory requires O(N^2) operatio ns and solving a dense linear system using naive direct methods (such as L U) requires O(N^3) operations. Both operations become computationally proh ibitive for large N. To address this\, large dense matrices are usually ap proximated using block low-rank representations\, commonly known as hierar chical matrices. In this talk\, I will discuss different types of hierarch ical matrices and how they can be used to design fast and scalable solvers . I’ll also show a few interesting applications that highlight the power of hierarchical matrices.

\n\nYuxin Ma

\nOn a shrink-and-ex pand technique for symmetric block eigensolvers
\nIn symmetric bloc k eigenvalue algorithms\, such as the subspace iteration algorithm and the locally optimal block preconditioned conjugate gradient (LOBPCG) algorith m\, a large block size is often employed to achieve robustness and rapid c onvergence. However\, using a large block size also increases the computat ional cost. Traditionally\, the block size is typically reduced after conv ergence of some eigenpairs\, known as deflation. In this work\, we propose a non-deflation-based\, more aggressive technique\, where the block size is adjusted dynamically during the algorithm. This technique can be applie d to a wide range of block eigensolvers\, reducing computational cost with out compromising convergence speed. We present three adaptive strategies f or adjusting the block size\, and apply them to four well-known eigensolve rs as examples. Detailed theoretical analysis and numerical experiments ar e provided to illustrate the efficiency of the proposed technique. In prac tice\, an overall acceleration of 20% to 30% is observed.

\n LOCATION:https://researchseminars.org/talk/MathMAC/44/ END:VEVENT BEGIN:VEVENT SUMMARY:Flora Philipp DTSTART:20251126T080000Z DTEND:20251126T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/45 DESCRIPTION:Title: Global Existence of Weak Solutions to Chemotaxis Navier-Stokes-Korteweg s ystems\nby Flora Philipp as part of Modelling of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\n\nAbstra ct\nA Chemotaxis compressible Navier–Stokes model was introduced to desc ribe vascular network formation. Global existence for this system was rece ntly shown for adiabatic exponent $\\gamma>8/5$ by Huo and\nJ\\“ungel. W e regularize the equations by adding a Korteweg term and prove global exis tence for the regularized system\, allowing for smaller adiabatic exponent s ($\\gamma>1$). Our analysis is based on the use of a free energy as well as the BD-entropy\, and exploits additional regularity properties derived via the systematic integration-by-parts technique introduced by J\\“ung el and Matthes. In the course of this\, we can also establish existence re sults for a broader class of Navier–Stokes–Korteweg systems\, which un til now have only been investigated in two special cases: the Quantum-Navi er–Stokes equation\nand the thin film equation.\n LOCATION:https://researchseminars.org/talk/MathMAC/45/ END:VEVENT BEGIN:VEVENT SUMMARY:P. Šácha\, A. Gazca\, P. Pelech DTSTART:20251203T080000Z DTEND:20251203T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/46 DESCRIPTION:Title: Semester seminar of junior researchers\nby P. Šácha\, A. Gazca\, P. Pelech as part of Modelling of materials - theory\, model reduction and e fficient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/46/ END:VEVENT BEGIN:VEVENT SUMMARY:V. Patočka\, L. Lebec\, O. Chrenko DTSTART:20251210T080000Z DTEND:20251210T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/47 DESCRIPTION:Title: Semester seminar of junior researchers\nby V. Patočka\, L. Lebec\, O . Chrenko as part of Modelling of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/47/ END:VEVENT BEGIN:VEVENT SUMMARY:M. Outrata\, M. Fehling\, J. Blechta DTSTART:20251217T080000Z DTEND:20251217T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/48 DESCRIPTION:Title: Semester seminar of junior researchers\nby M. Outrata\, M. Fehling\, J. Blechta as part of Modelling of materials - theory\, model reduction an d efficient numerical methods (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/48/ END:VEVENT BEGIN:VEVENT SUMMARY:Giulio Giusteri DTSTART:20260128T080000Z DTEND:20260128T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/49 DESCRIPTION:Title: Mathematical modeling of viscoelastic fluids\nby Giulio Giusteri as p art of Modelling of materials - theory\, model reduction and efficient num erical methods (UNCE MathMAC)\n\n\nAbstract\nA class of continuum mechanic al models aimed at describing the behaviorof viscoelastic materials will b e presented. These models are obtained by incorporating concepts originate d in the theory of solid plasticity in a fluid mechanics context [1]. With in this class\, even a simple model with constant material parameters is a ble to qualitatively reproduce a number of experimental observations in bo th simple shear and extensional flows\, including linear viscoelastic prop erties\, the rate dependence of steady-state material functions\, the stre ss overshoot in incipient shear flows\, and the difference in shear and ex tensional rheological curves.\n\nThese constitutive models are based on a logarithmic relation between the elastic strain measure and the stress ten sor and on evolution equations for a local representative of the elastical ly-relaxed strain state. Importantly\, it can be shown that classical mode ls are recovered by expanding the evolution equation for the elastic stres s around the null solution. The mathematical analysis of such tensorial tr ansport equations leads to the definition of the notion of charted weak so lutions [2]. These are based on non-standard a priori estimates that invol ve both viscous and plastic energy dissipation. The main aspects and open problems of the theoretical analysis of the evolution equations will be pr esented.\n\n[1] M. A. H Alrashdi\, G. G. Giusteri\, Evolution of local rel axed states and the modeling of viscoelastic fluids\, Phys. Fluids\, 36\, 093129\, 2024.\n[2] G. Ciampa\, G. G. Giusteri\, A. G. Soggiu\, Viscoelast icity\, logarithmic stresses\, and tensorial transport equations\, Math. M eth. Appl. Sci. 48\, 2934--2953\, 2025.\n LOCATION:https://researchseminars.org/talk/MathMAC/49/ END:VEVENT BEGIN:VEVENT SUMMARY:Umberto Zerbinati DTSTART:20260211T080000Z DTEND:20260211T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/50 DESCRIPTION:Title: Structure-Preserving FEEC Methods for Spectral and Pseudospectral Analysi s of Dynamo Operators\nby Umberto Zerbinati as part of Modelling of ma terials - theory\, model reduction and efficient numerical methods (UNCE M athMAC)\n\n\nAbstract\nNumerical dynamo problems involve advection–diffu sion operators whose spectral and pseudospectral properties play a central role in determining growth rates\, stability\, and transient amplificatio n. Their reliable numerical approximation remains challenging\, particular ly in advection-dominated and strongly non-normal regimes. In this talk\, I present a structure-preserving finite element exterior calculus (FEEC) f ramework for dynamo-type advection–diffusion operators acting on differe ntial forms. The discretization is based on finite element de Rham complex es and preserves the geometric and topological structure of the continuous problem. Within this setting\, we investigate the approximation of spectr a and pseudospectra and derive a priori error estimates for pseudospectral convergence. We also discuss the role of exponential transformations for advection–diffusion operators and their consequences for the asymptotic behavior of solutions.\n LOCATION:https://researchseminars.org/talk/MathMAC/50/ END:VEVENT BEGIN:VEVENT SUMMARY:Vít Dolejší DTSTART:20260218T080000Z DTEND:20260218T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/51 DESCRIPTION:Title: Adaptive domain decomposition preconditioners for time-dependent flow pro blems\nby Vít Dolejší as part of Modelling of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\n\nAbstra ct\nWe deal with the numerical solution of the time/dependent compressible Navier-Stokes equations by the space-time adaptive discontinuous Galerkin method (DGM). It involves adaptive choice of the time steps and anisotrop ic hp-mesh adaptation. The discretization leads to a sequence of large alg ebraic systems which are solved by GMRES method with domain decomposition based preconditioners.\nParticularly\, we focus on two-level additive and hybrid Schwarz techniques which can be easily treated in the context of DG M. We study the convergence of the linear solver in dependence on the numb er of subdomains and the number of element of the coarse grid. We propose a simplified cost model measuring the computational costs in terms of floa ting-point operations\, the speed of computation\, and the wall-clock time for communications among computer cores. Moreover\, the cost model serves as a base of the presented adaptive domain decomposition method which cho ose the number of subdomains and the number of element of the coarse grid in order to minimize the computational costs. The efficiency of the propos ed technique is demonstrated by two benchmarks of compressible flow simula tion.\n LOCATION:https://researchseminars.org/talk/MathMAC/51/ END:VEVENT BEGIN:VEVENT SUMMARY:Jakub Cach DTSTART:20260304T080000Z DTEND:20260304T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/52 DESCRIPTION:Title: A thermodynamically consistent Johnson-Segalman-Giesekus model: numerical simulation of the rod climbing effect\nby Jakub Cach as part of Model ling of materials - theory\, model reduction and efficient numerical metho ds (UNCE MathMAC)\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/MathMAC/52/ END:VEVENT BEGIN:VEVENT SUMMARY:Vít Průša DTSTART:20260311T080000Z DTEND:20260311T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/53 DESCRIPTION:Title: Discrete versus continuous-linear lattice models and their exact continuo us counterparts\nby Vít Průša as part of Modelling of materials - t heory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\n \nAbstract\nWe discuss the correspondence between discrete linear lattice/ chain models of interacting particles and their continuous counterparts re presented by linear partial differential equations. In particular\, we stu dy the correspondence problem for linear nearest neighbour interaction lat tice models as well as for linear multiple-neighbour interaction lattice m odels\, while we gradually proceed from infinite lattices to periodic latt ices and finally to finite lattices with fixed ends/zero Dirichlet boundar y conditions. The whole study is framed as a systematic specialisation of Fourier analysis tools from the continuous to the discrete setting and vic e versa\, and the correspondence between the discrete and continuous model s is examined primarily with regard to the dispersion relation.\n LOCATION:https://researchseminars.org/talk/MathMAC/53/ END:VEVENT BEGIN:VEVENT SUMMARY:Eduard Feireisl DTSTART:20260318T080000Z DTEND:20260318T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/54 DESCRIPTION:Title: Well posedness of the Euler system of gas dynamics\nby Eduard Feireis l as part of Modelling of materials - theory\, model reduction and efficie nt numerical methods (UNCE MathMAC)\n\n\nAbstract\nWe discuss the well pos edness of the Euler system of gas dynamics from two different perpectives: \n1. Admissible solutions are inviscid limits of the Navier-Stokes-Fourier system.\n2. Admissible solutions comply with the maximum entropy producti on principle.\nWe show that these two criteria are in general not compatib le and give rise to different classes of solutions.\n\nThen we propose and admissibility criterion that gives rise to a unique solution semigroup of the Euler system in the class of generalized dissipative solutions. The s olutions are Borel measurable meaning ``almost'' continuous with respect t o the initial data.\n LOCATION:https://researchseminars.org/talk/MathMAC/54/ END:VEVENT BEGIN:VEVENT SUMMARY:Kaibo Hu DTSTART:20260325T080000Z DTEND:20260325T090000Z DTSTAMP:20260422T090347Z UID:MathMAC/55 DESCRIPTION:Title: Modelling Generalized Continua with Homological Algebra\nby Kaibo Hu as part of Modelling of materials - theory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\n\nAbstract\nStructure-preserving disc retization within the frameworks of Finite Element Exterior Calculus (FEEC ) and Finite Element Tensor Calculus (FETC) motivates the investigation of the differential structures underlying physical models\, namely\, the spa ces in which variables reside and the differential operators that connect them. These structures are encoded in differential complexes and their ass ociated cohomology. In computational electromagnetism\, discretizing the e ntire differential complex avoids spurious solutions and yields many desir able properties.\n\nRecent efforts to extend this perspective to continuum mechanics have also led to progress in modelling. In elasticity\, strain and stress tensors fit naturally into the elasticity (Calabi\, Kröner) co mplex\, which can be viewed as a special case of the Bernstein–Gelfand –Gelfand (BGG) construction. The intermediate steps in the BGG construct ion turn out to correspond to continuum microstructures\, such as the Coss erat model. From this viewpoint\, the BGG construction can be interpreted as a cohomology-preserving elimination of microstructural degrees of freed om.\n\nIn this talk\, we explore mechanical models\, such as classical ela sticity\, the Cosserat model\, various plate models (dimension reduction)\ , continuum defects\, and mixed-dimensional models\, through the lens of d ifferential complexes\, the BGG machinery\, and the Čech complex.\n LOCATION:https://researchseminars.org/talk/MathMAC/55/ END:VEVENT BEGIN:VEVENT SUMMARY:Jelena Radovič DTSTART:20260401T070000Z DTEND:20260401T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/56 DESCRIPTION:Title: High-resolution street-scale modeling with LES models\nby Jelena Rado vič as part of Modelling of materials - theory\, model reduction and effi cient numerical methods (UNCE MathMAC)\n\n\nAbstract\nAs the sustainabilit y implementation requirements at the urban level are far-reaching due to e xtreme weather and climate events\, the need for adequate\, efficient\, an d high-fidelity modelling tools also increases. Cities lack the resilience to withstand extreme events\, and the vulnerability of urban dwellers is elevated. Today\, air quality and thermal comfort deterioration in urban e nvironments are central concerns that shape mitigation policies and urban climate research. However\, finding an appropriate way to understand the l ocal urban atmosphere\, recognise issues\, and produce reliable informatio n and solutions is complex and multibranched. It requires not only high-en d numerical tools\, software\, observation networks\, and urban datasets\, but also careful planning\, interpretation\, and cooperation between the expert community and public administration.\n\nThe cornerstone of any scie ntific investigation of certain phenomena lies in understanding the physic al processes that drive them and govern their evolution. The physical fram ework of the urban boundary layer is a delicate balance of various physica l processes that affect the urban atmosphere\, airflow\, and phenomena wit hin it. This framework is simultaneously influenced by urban morphology an d the specificity of settlement patterns. Despite being distinctive on a b roader scale\, urban areas share a common trait of being heterogeneous wit h a range of artificial and natural surfaces covering them. Along with lar ge-scale atmospheric dynamics\, human activities\, etc.\, these traits mak e cities hotbeds for turbulence generation. Turbulence is a governing mech anism shaping urban atmospheric behaviour\, energy balance\, pollutant tra nsport\, and street-scale airflow dynamics. It is certainly fundamental an d needs to be adequately resolved\, with its influence on the urban atmosp heric processes accurately represented in the models. Resolving the urban morphology and the boundary layer on a fine scale via numerical models is a prerequisite for understanding urban ventilation\, air quality\, and the rmal comfort and progressing in climate change adaptation and mitigation.\ n\nThis presentation addresses these critical urban climate issues by util ising Large-Eddy Simulation (LES) to achieve high-resolution\, street-scal e modelling. The Parallelized Large-Eddy Simulation Model (PALM)\, a state -of-the-art computational framework designed specifically for the urban ca nopy is introduced. The presentation will detail PALM’s advanced capabil ities\, including its sophisticated treatment of urban surfaces\, plant ca nopy effects\, and high-resolution turbulence resolving features.\n LOCATION:https://researchseminars.org/talk/MathMAC/56/ END:VEVENT BEGIN:VEVENT SUMMARY:Patrick Farrell DTSTART:20260408T070000Z DTEND:20260408T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/57 DESCRIPTION:Title: A kinetic theory approach to ordered fluids\nby Patrick Farrell as pa rt of Modelling of materials - theory\, model reduction and efficient nume rical methods (UNCE MathMAC)\n\n\nAbstract\nBoltzmann derived the kinetic equation for monatomic gases in 1872. It took 85 years before Curtiss deve loped the extension to polyatomic gases\, enlarging the phase space with E uler angles to describe the orientations of the molecules. What is the rig ht kinetic equation for molecules with other kinds of internal ordering\, such as the rodlike molecules constituting liquid crystals? This talk pres ents a framework that aims to address exactly this question.\n\nThe intern al structure of a molecule is described by a point on an order parameter m anifold\, a concept introduced by Capriz in continuum mechanics in 1989. W ith this manifold\, a group action describing how rotations change orderin g\, and the intermolecular potential\, we derive a general BBGKY hierarchy and a Vlasov—Boltzmann kinetic equation that governs the evolution the one-particle density function.\n\nWe prove that in certain situations the system thermalises to a Maxwellian distribution\, simulate the resulting n ovel kinetic equation for liquid crystals with direct simulation Monte Car lo\, and discuss taking hydrodynamic closures to derive novel models at th e level of continuum mechanics.\n LOCATION:https://researchseminars.org/talk/MathMAC/57/ END:VEVENT BEGIN:VEVENT SUMMARY:Jooyoung Hahn DTSTART:20260415T070000Z DTEND:20260415T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/58 DESCRIPTION:Title: Finite Volume Method for Level Set Equations on Polyhedral Meshes\nby Jooyoung Hahn as part of Modelling of materials - theory\, model reductio n and efficient numerical methods (UNCE MathMAC)\n\n\nAbstract\nWe propose a cell-centered finite volume method to numerically solve the G-equation model in premixed turbulent combustion. The G -equation is a standard leve l set equation containing the advective\, normal\, and mean curvature term s. Compared to conventional algorithms to solve level set equations on a p olyhedron mesh\, the proposed scheme has mainly three advantages. The firs t is that it numerically shows higher order of convergence on polyhedral m eshes. The second is that the implementation of parallel computing using d omain decomposition with 1-ring face neighborhood structure can be done st raightforwardly by a standard cell-centered finite volume code. The third is that a time step restriction caused by the CFL condition is reduced by the proposed semi-implicit scheme. Numerical examples computed on polyhedr al meshes are presented to verify the numerical properties of the proposed algorithm in the case of each velocity term in the G-equation.\n LOCATION:https://researchseminars.org/talk/MathMAC/58/ END:VEVENT BEGIN:VEVENT SUMMARY:Giuseppe Saccomandi DTSTART:20260422T070000Z DTEND:20260422T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/59 DESCRIPTION:Title: A Road Map for Nonlinear Elastodynamics\nby Giuseppe Saccomandi as pa rt of Modelling of materials - theory\, model reduction and efficient nume rical methods (UNCE MathMAC)\n\n\nAbstract\nNonlinear elastodynamics lies at the core of many contemporary challenges in mechanics\, ranging from wa ve propagation in complex media to the modeling of soft materials and biol ogical tissues. Despite significant advances\, the current theoretical and computational frameworks often remain rooted in classical continuum assum ptions\, which may be inadequate to capture key phenomena such as dispersi on\, multiscale interactions\, and the influence of microstructural discre teness.\nThis talk presents a critical overview of the state of the art in nonlinear elastodynamics and proposes a forward-looking research agenda. After revisiting the main achievements of classical and weakly nonlinear t heories\, particular emphasis is placed on their limitations in describing strongly nonlinear wave phenomena and materials with complex internal str ucture.\nThe discussion will highlight several open problems\, including t he role of microstructure in macroscopic wave dynamics\, the identificatio n and validation of constitutive models beyond the classical paradigm\, an d the interplay between nonlinearity\, dispersion\, and dissipation. \nTh e talk concludes by outlining a possible roadmap for future developments. The aim is to stimulate a more unified and rigorous framework for nonlinea r elastodynamics\, capable of addressing emerging applications in engineer ing and applied science.\n LOCATION:https://researchseminars.org/talk/MathMAC/59/ END:VEVENT BEGIN:VEVENT SUMMARY:Bruno Blais DTSTART:20260429T070000Z DTEND:20260429T080000Z DTSTAMP:20260422T090347Z UID:MathMAC/60 DESCRIPTION:Title: High-order matrix-free methods for dense particle-laden flows: An open-so urce perspective\nby Bruno Blais as part of Modelling of materials - t heory\, model reduction and efficient numerical methods (UNCE MathMAC)\n\n \nAbstract\nThe simulation of flows using computational fluid dynamics (CF D) has advanced considerably in recent decades and is now an essential too l across industries ranging from aerospace design to process engineering. Although CFD is relatively mature for single-phase flows\, particle-laden flows remain significantly more challenging to simulate\, in part due to t heir intrinsic multiscale nature: particle–fluid interactions at the par ticle length scale propagate across all length scales. Inherently opaque\, these flows are extremely difficult to study experimentally\, and simulat ion remains one of the most viable strategies for gaining insight into the ir internal dynamics. Among the wide variety of simulation models for part icle-laden flows\, Euler–Lagrange approaches are particularly appealing owing to their capacity to describe individual rigid particles explicitly. Two main classes of Euler–Lagrange models can be distinguished: Resolve d (REL) and Unresolved (UREL). Resolved models discretize the fluid equati ons at a scale finer than the particles and enforce the no-slip boundary c ondition at the solid–fluid interface\, typically through an immersed bo undary method. While accurate\, this approach is highly computationally in tensive\, which limits the number of particles that can feasibly be simula ted. Unresolved models instead filter the Navier–Stokes equations and tr eat particles as point momentum sources\, greatly reducing the computation al cost at the expense of requiring accurate closure models. This talk pre sents our efforts in designing Lethe\, an open-source\, high-order multiph ysics framework for single- and multiphase flows built on the deal.II libr ary. We first motivate the use of high-order finite elements for CFD appli cations in process engineering. After discussing the challenges associated with our high-order stabilized formulation\, we introduce matrix-free met hods as a paradigm that alleviates several of these difficulties. We then present the implementation of a matrix-free stabilized Navier–Stokes sol ver within Lethe and demonstrate its capabilities for turbulent flow simul ations. Building on this foundation\, we describe both our REL and UREL im plementations for particle-laden flows and illustrate their capabilities t hrough selected applications. For REL\, we demonstrate the model’s abili ty to accurately capture the dynamics of individual particles by investiga ting the sedimentation of spherical and non-spherical bodies. For UREL\, w e show that this approach can simulate the dynamics of large numbers of pa rticles in complex systems. We conclude by reflecting on the potential of high-order methods for particle-laden flows\, the role of opensource softw are in developing accurate and efficient simulation tools for these comple x systems\, and some of the lessons learned during the development of Leth e. Finally\, we outline future directions for this work\, including the de velopment of more accurate closure models for UREL and the extension of ou r framework to additional multiphysics applications.\n LOCATION:https://researchseminars.org/talk/MathMAC/60/ END:VEVENT END:VCALENDAR