Scientific Organisers
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David Acreman, Hewlett Packard Enterprise
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Jemma Shipton, University of Exeter
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Beth Wingate, University of Exeter
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Hiroe Yamazaki, Imperial College London
Keynote Speakers:
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Giancarlo Antonucci, UK Atomic Energy Authority
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Rob Falgout, Lawrence Livermore National Laboratory
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Josh Hope-Collins, Imperial College London
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Felix Kwok, Université Laval
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Juliane Rosemeier, Freie Universität Berlin
About:
Efficient computation of solutions to partial differential equations on modern supercomputers is crucial for many scientific applications such as weather and climate prediction, fusion modelling, molecular dynamics and engineering applications. As we have reached the limit of Dennard scaling, which previously guaranteed faster processors due to smaller components, modern supercomputers now have orders of magnitude more processors than previous generations. Exascale supercomputers are capable of 10^18 floating point operations per second but making full use of this hardware for the solution of partial differential equations requires a deep understanding of the mathematical properties of the governing equations and how to discretise them in a way that enables calculations to be performed concurrently, that is in parallel.
Parallel-in-time algorithms, the topic of this workshop, enable parallel computation in the time domain, in addition to more traditional parallelism through spatial domain decomposition. Time-parallelism is significantly more challenging than spatial parallelism due to causality, since the state of the system at future times must depend on that at past times. However, the advent of the exascale era has inspired recent research in to these algorithms, leading to an explosive increase in the number of different algorithms available. The efficiency of these algorithms depends on tailoring the algorithm to the equations being solved and this requires interdisciplinary collaboration both with the application experts and with mathematicians working in adjacent areas.
This workshop will bring together such an interdisciplinary group of people to advance our understanding of these algorithms and open up new areas of collaboration and research.
Programme
| MONDAY 7 JULY 2025 | |||
| 10.00 – 10.30 | Registration | ||
| 10.30 - 12.00 | Training session (optional) | ||
| 12.00 - 13.30 | Lunch | + registration if not attending training session | |
| 13.30 - 14.30 | Josh Hope-Collins, Imperial College London | ParaDiag preconditioners for nonlinear and variable-coefficient problems | |
| 14.30 - 15.00 | Ryo Yoda, University of Wuppertal | Toward efficient solvers using block-epsilon circulant preconditioning on modern integrated CPU-GPU systems | |
| 15.00 - 15.30 | Refreshments | ||
| 15.30 – 16.00 | Andreas Schafelner, Johannes Kepler University Linz | A parallel-in-time solver for nonlinear degenerate time-periodic parabolic problems | |
| 16.00 - 16.30 | Alexander Schell, University of Münster | Towards Vectorised Block Krylov Parallel in Time Methods | |
| 16.30 – 17.30 | Welcome Reception | ||
| TUESDAY 8 JULY 2025 | |||
| 09.15 – 10.15 | Juliane Rosemeier, Freie Universität Berlin | Multilevel Parareal Methods and Standard Form Transformations for Weakly Nonlinear Problems | |
| 10.15 – 10.45 | Werner Bauer, University of Surrey | Accurate solutions of highly oscillatory systems under large time steps using higher-order phase averages | |
| 10.45 – 11.15 | Refreshments | ||
| 11.15 - 11.45 | Martin Gander, Université de Genève | Parareal for hyperbolic problems just does not work, or does it? | |
| 11.45 - 12.15 | Stephan Rave, University of Münster | A Parareal Algorithm with Spectral Coarse Solver | |
| 12.15 - 12.45 | Joao Guilherme Caldas Steinstraesser, University of Sao Paulo | Stability and numerical study of Parareal and MGRIT applied to the shallow water equations on the rotating sphere | |
| 12.45 – 14.15 | Lunch | ||
| 14.15 – 14.45 | Daniel Ruprecht, Hamburg University of Technology | Machine learning based coarse propagators for Parareal | |
| 14.45 - 15.15 | Massimiliano Tamborrino, University of Warwick | ProbParareal: A Probabilistic Numerical Parallel-in-Time Solver for Differential Equations | |
| 15.15 – 15.45 | Refreshments | ||
| 15.45 - 16.15 | Abdelouahed Ouardghi, Jülich Supercomputing Centre/ Forschungszentrum Jülich | Space-Time Parallelism using Spectral Deferred Corrections and Finite Elements for Incompressible Navier–Stokes Equations | |
| 16.15 - 16.45 | Thomas Baumann, Forschungszentrum Juelich | Diagonal Spectral Deferred Correction for 3D Rayleigh-Benard convection | |
| 16.45 - 17.15 | Alex Brown, Met Office/ University of Exeter | A comparison of time-parallel "across the method" deferred correction schemes for atmospheric modelling | |
| WEDNESDAY 9 JULY 2025 | |||
| 09.15 – 10.15 | Giancarlo Antonino Antonucci, UKAEA | Time-parallel algorithms for chaotic systems | |
| 10.15-10.45 | Sriramkrishnan Muralikrishnan, Jülich Supercomputing Centre/ Forschungszentrum Jülich GmbH | A Massive Space-Time Parallel Particle-In-Fourier Framework for Kinetic Plasma Simulations | |
| 10.45 – 11.15 | Refreshments | ||
| 11.15 - 11.45 | Thibaut Lunet, Hamburg University of Technology | Spectral Deferred Correction: from theoretical analysis to design of new time-parallel algorithms | |
| 11.45 - 12.15 | Lisa Wimmer, Bergische Universität Wuppertal | On the application of spectral deferred corrections to differential-algebraic equations | |
| 12.15 - 12.45 | Hans Johansen, Lawrence Berkeley National Laboratory | New approaches to space-time splitting with higher accuracy | |
| 12.45 | Lunch and free afternoon | ||
| THURSDAY 10 JULY 2025 | |||
| 09.15 – 10.15 | Rob Falgout, Lawrence Livermore National Laboratory | Parallel-in-Time Solution of Hyperbolic PDE Systems via Characteristic-Variable Block Preconditioning | |
| 10.15 – 10.45 | David Vargas, Sandia National Laboratories | Parallel multigrid in time for chaos with timescale-independent convergence | |
| 10.45 – 11.15 | Refreshments | ||
| 11.15 - 11.45 | Arne Naaegel, Goethe University Frankfurt | Scalable parallel-in-time solvers for linear poroelasticty | |
| 11.45 – 12.15 | Wiebke Drews, TU Dortmund University | Stabilized Finite Element Multigrid Techniques for Space-Time Parallelism in Convection-Diffusion Problems | |
| 12.15 – 12.45 | Julius Ehigie, University of Lagos | Parallelizing Internal Stages in High-Order Two-Derivative DIRK Methods with applications | |
| 12.45 – 14.15 | Lunch | ||
| 14.15 – 15.15 | Felix Kwok, Université Laval | Optimized Schwarz methods in time for discrete transport control | |
| 15.15 – 15.45 | Sebastian Götschel, Hamburg University of Technology | Parallelization in time for inverse problems | |
| 15.45 - 16.15 | Refreshments | ||
| 16.15 – 16.45 | Nick Janssens, KU Leuven | Parallel-in-time multiple shooting using large-eddy simulation for flow reconstruction in the atmospheric boundary layer | |
| 16.45 – 17.15 | Bernhard Heinzelreiter, University of Edinburgh | A Diagonalization-Based Parallel-in-Time Preconditioner for Instationary Flow Control Problems | |
| 19.00 onwards | Workshop Dinner at Apex Grassmarket Hotel | The Heights Room, Apex Grassmarket Hotel, 31-35 Grassmarket, Edinburgh EH1 2HS | |
| FRIDAY 11 JULY 2025 | |||
| 09.15 – 09.45 | Magnus Appel, University of Southern Denmark | Towards Fast Topology Optimisation of Transient Heat Conduction Using Space-time Multigrid Methods | |
| 09.45 – 10.15 | Sean Hon, Hong Kong Baptist University | An optimal parallel-in-time preconditioner for parabolic optimal control problems | |
| 10.15 – 10.45 | Mahadevan Ganesh, Colorado School of Mines | Parallel-in-time-and-space simulation for a class of models with non-local operators | |
| 10.45 – 11.15 | Refreshments | ||
| 11.15 - 12.30 | Closing discussion | ||
| 12.30 | Lunch |