'Enabling mixed-precision with the help of tools: A Nekbone case study' at PPAM24
2024-09-09 12:05 - 12:25 (Europe/Paris) | Ostrava, Czechia, Ostrava, Czech Republic
If you’re going to PPAM24 September 8 – 11 in Ostrava, Czechia, make sure to check out the talk by Yanxiang Chen from our partner UMU on their progress implementing and optimizing mixed precision in Nekbone toward its integration in Neko and NekRS. The accompanying paper is also available as a pre-print online: https://arxiv.org/pdf/2405.11065

Call for Abstracts! High-fidelity CFD with application in ship hydrodynamics
2024-12-15 00:00 - 23:59
Submit your abstract to our invited session at Marine 2025!!
The session titled “High-fidelity CFD with application in ship hydrodynamics” is seeking submissions by December 15th, 2024. Full details and guidelines for submission are available in the proposal .
You can also check out the invited session’s page on the conference website.

Mixed-Precision and Energy-Efficient Computations
2025-06-10 15:00 - 2025-06-12 16:00
As supercomputers get bigger, they become both more capable of solving complex problems and consuming enormous amounts of energy. To ensure their sustainability, we must start focusing on reducing energy-to-solution at least as much as we focus on reducing time-to-solution. One of the ways CEEC is working on this is using mixed precision.
Join Yanxiang Chen at ISC in the Foyer D-G – on the 2nd floor to learn about our latest work reducing precision and energy consumption without compromising accuracy.

CEEC at ISC25
2025-06-11 13:00 - 13:20
Join our own Niclas Jansson at the Euro HPC JU booth for a presentation on our project and progress so far!

RESEARCH POSTER PITCH with Yanxiang Chen
2025-06-11 13:30 - 14:15
After listening to Niclas Jansson present our project at the EuroHPC JU booth at 1pm, strole over to Hall E to hear from our own Yanxiang Chen.
If you want the chance to ask questions about how we’re using mixed precision to drive energy-to-solution down without compromising accuracy, make sure to stop by the research poster pitch !
Yanxiang will present and answer questions about his poster Mixed-Precision and Energy-Efficient Computations.

FLEXI: Scale-resolving simulations of compressible turbulence on modern HPC systems
2025-08-27 16:20 - 16:40 | TUD Dresden University of Technology Barkhausen-Bau (BAR), Georg-Schumann-Str. 13 , Dresden, 01069, Germany
Join our own Anna Schwarz for the WHPC Europa invited session discussing our latest work preparing FLEXI for exascale and GPU-based systems.
Abstract
The application of scale-resolving simulations such as LES and DNS remains challenging in numerous engineering applications due to the substantial computational demands and the limited available computational resources. It was thoroughly demonstrated in the last decade that high-order numerical methods show significant advantages in terms of computational cost required to achieve a given accuracy for DNS and LES and that they can be implemented efficiently on traditional CPU-based system architectures. However, the improvements in performance for CPU-based systems has slowed down significantly over the last years. Consequently, more specialised architectures, such as GPUs, have become increasingly popular in the last decade. These architectures still promise considerable performance improvements per generation and thus allow more complex flow cases to be tackled, while also yielding better performance per invested amount of energy. However, CPU codes cannot be easily run on GPU hardware, since they exhibit a distinctly different architecture and require different programming languages. In this talk it is demonstrated how existing codebases can be translated efficiently to GPU hardware, both in terms of implementation effort and computational performance. For this, the unstructured DG code FLEXI~cite{Krais2019,Kempf2024} is utilized as an example. Finally, it is shown that FLEXI is capable of tackling challenging large-scale problems with complex geometries on modern HPC systems.

Exploring Flow Fields at Scale: GPU-Accelerated Scientific Visualization for Exascale CFD
2025-08-27 16:40 - 17:00 | TUD Dresden University of Technology Barkhausen-Bau (BAR), Georg-Schumann-Str. 13 , Dresden, 01069, Germany
Join our own Susanne Malheiros at the WHPC Europa Invited Session to hear about our latest work on Vistle.
Abstract:
This talk presents the ongoing efforts to port Vistle – a software for creating immersive extended reality visualizations of scientific data – to the GPU by integrating the portable visualization toolkit Viskores. The approach is illustrated by sample computational fluid dynamics (CFD) visualizations of the light-house cases from the Center of Excellence in Exascale CFD (CEEC) project.

Mixed-Precision and Energy-Efficient Computations
2025-10-09 12:10 - 14:30
If you’re at the Workshop on Approximate Computing in Numerical Linear Algebra in Paris this week, don’t miss Yanxiang Chen’s lunch poster talk on mixed precision and energy efficient computations!
Abstract: High Performance Computing has traditionally focused on optimizing between memory usage, arithmetic intensity, parallelism, and communication costs. However, as simulations grow, energy consumption has surged, presenting significant sustainability challenges for large-scale computing infrastructures. Addressing these challenges requires innovative strategies that enhance energy efficiency without compromising computational accuracy or performance.
We present a systematic methodology for reducing the energy footprint of large-scale simulations via mixed-precision computing, without compromising accuracy or performance. Our approach combines performance profiling with numerical sensitivity analysis to identify precision-insensitive code regions, select promising candidates, and gradually convert them to lower precision. Applied to representative high-performance computing kernels, this strategy yields up to 40% speedup and 47% energy savings in an implicit Poisson solver, and roughly 30% gains in both execution time and energy consumption in explicit solvers, all while preserving double-precision level accuracy. These results demonstrate that our methodology provides a versatile and effective lever for enhancing the sustainability of HPC applications.

Mixed-Precision Strategies in Spectral Element Codes: Accuracy-Aware Approximation for Energy-Efficient Simulations
2025-10-09 15:50 - 16:10
If you’re at the Workshop on Approximate Computing in Numerical Linear Algebra in Paris this week, chec out Roman Iakymchuk’s talk on mixed-precision strategies in spectral element codes on Thursday!
Abstract: Approximate computing via mixed precision arithmetic offers a promising path to energy-efficient high-performance computing. However, identifying where and how to apply reduced precision without compromising solution accuracy remains a key challenge in scientific simulations. In this talk, we present a comprehensive methodology for enabling mixed-precision in spectral element codes using floating-point analysis tools, roofline modeling, and empirical verification. We apply our strategy to Nekbone and Neko—two fluid dynamics solvers—by combining reduced-precision iterative solvers with double-precision critical operations such as dot products and global communications. Our method is supported by Verificarlo’s Monte Carlo arithmetic and precision emulation, which help detect numerically stable kernels for approximation. The resulting mixed-precision versions deliver up to 2.38x faster time-to-solution and 2.8× lower energy-to-solution, while retaining double-precision-level accuracy. This work highlights a practical, accuracy-aware approach to integrating approximation into large-scale legacy applications, making them fit for future exascale platforms.

Task-decomposed Overlapped Preconditioner for Sustained Strong Scalability on Accelerated Exascale Systems
2026-01-28 11:30 - 12:00
Join Niclas Jannson in Osaka, Japan at SCA/HPCAsia2026 for his talk on “Task-decomposed Overlapped Preconditioner for Sustained Strong Scalability on Accelerated Exascale Systems.”

A Matrix-Free Algebraic hp-Multigrid Method for Computational Fluid Dynamics Applications
2026-01-28 12:00 - 12:30
After the talk on preconditioners in Osaka, Japan at SCA/HPCAsia2026 , stick with Niclas Jannson for his next talk on “A Matrix-Free Algebraic hp-Multigrid Method for Computational Fluid Dynamics Application., a best paper finalist. “

CEEC at the 1st Stuttgart Research Software Day
2026-03-02 16:45 - 18:30
What is research software and why does it matter? These questions are the point of the first ever Research Software Day at the University of Stuttgart. Come learn about the CEEC codes FLEXI/GALAXI during the poster session and stay to learn about what else is being developed on campus.

FAIR-FLEXI - A Trustworthy CFD Code for Simulation and Training
2026-03-03 16:10 - 16:30
Engineering and science disciplines, especially computational fluid dynamics (CFD) generate massive amounts of research data, but they can only become knowledge if they can be shared and explored through data analytics and AI. This, in turn, requires a FAIR (findable, accessible, interoperable, reusable) infrastructure. For complex research software, however, FAIR goes far beyond being open-source: reproducibility is hindered by hidden expertise such as user-defined parameters, compile options, hardware constraints, and third-party dependencies.
This talk outlines the design, implementation, and lessons learned from FAIR-FLEXI. We discuss how comprehensive provenance capture, portable environments, and interactive notebooks turn CFD workflows into trustworthy, reproducible research assets.

GALAEXI: An Architecture-Agnostic GPU-Acceleration Approach for Legacy Fortran Software
2026-03-03 18:25 - 18:50
Join Spencer Starr at the Society for Industrial and Applied Mathematics (SIAM)Processing for Scientific Computing (PP26)confrence in Berlin for his talk on “GALAEXI: An Architecture-Agnostic GPU-Acceleration Approach for Legacy Fortran Software”
GALAEXI is a high-order discontinuous Galerkin spectral element method (DGSEM) computational fluid dynamics (CFD) code used for the study of compressible, turbulent flows. It is the device-accelerated version of an existing Fortran-based, CPU-only CFD framework. In this talk, the chosen strategy for porting the Fortran-based compute kernels in GALAEXI to CUDA/HIP C++ is covered. Included are discussions on managing device memory, retaining support for CPU computations, strategies for writing and testing kernels and how to handle GPU-to-GPU MPI communication. Specific emphasis is placed on how the strategies covered can be abstracted in an architecture-agnostic way to allow the greatest degree of portability. The information presented will then be distilled into advice for those seeking to perform a similar porting effort.
