Mini-Symposium 4: Modernizing CFD: Exploring CI/CD for Improved Software Development Life Cycle
2024-09-02 00:00 - 2024-09-03 23:59 (Europe/Paris) | Universitätsclub Bonn e.V., Konviktstr.9, Bonn, 53113, Germany
Join CEEC at the 35th Parallel CFD International Conference 2024 this fall in Bonn, Germany.
In the Mini-Symposium 4: Modernizing CFD: Exploring CI/CD for Improved Software Development Life Cycle, CEEC will be joined by sister European Centers of Excellence EXCELLERAT P2, EOCOE3, and HIDALGO 2 supported by the coordination activity CASTIEL 2. This symposium will focus on the role of Continuous Integration/Continuous Deployment (CI/CD) in guaranteeing CFD simulation applications’ stability, reproducibility, portability, and performance.

A continuous benchmarking pipeline for performance engineering on different architectures for the waLBerla framework
2024-09-03 16:50 - 17:10 (Europe/Paris) | Universitätsclub Bonn e.V., Konviktstr.9, Bonn, 53113, Germany
Come listen to our own Kajol Kulkarni presenting in mini-symposium 4 at parCFD on our work with benchmarking of waLBerla.

Keynote Lecture at parCFD
2024-09-03 18:15 - 19:00 (Europe/Paris) | Universitätsclub Bonn e.V., Konviktstr.9, Bonn, 53113, Germany
Join our own Niclas Jansson for his keynote lecture as an invited speaker at the 35th Parallel CFD International Conference 2024 in Bonn, Germany.

'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 (Europe/Paris)
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 (Europe/Paris)
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 (Europe/Paris)
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 (Europe/Paris)
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 (Europe/Paris) | 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 (Europe/Paris) | 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 (Europe/Paris)
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 (Europe/Paris)
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 (Europe/Paris)
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 (Europe/Paris)
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 (Europe/Paris)
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 (Europe/Paris)
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 (Europe/Paris)
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.

Calibration of Analytical Suction Bucket Installation Models Using Grain-Scale LBM-DEM Simulations
2026-06-11 08:10 - 08:30 (Asia/Tokyo)
If you’re at the 45th International Conference on Ocean, Offshore & Arctic Engineering (OMAE2026) in Tokyo this June, don’t miss the presentation from our own Samual Kemmler on “Calibration of Analytical Suction Bucket Installation Models Using Grain-Scale LBM-DEM Simulations.”
Suction bucket foundations offer significant advantages for offshore wind applications, enabling fast and cost-efficient installation. However, installation failures due to piping erosion remain a critical challenge, particularly in loose or highly permeable seabeds. Understanding the interplay between seepage flow, soil properties, and foundation geometry during suction installation is essential for improving design guidelines and installation strategies.
In this contribution, fully-resolved numerical simulations are provided, that allow a detailed, grain-scale view of the suction installation process. A coupled Lattice Boltzmann-Discrete Element Method (LBM-DEM) framework is employed, in which fluid flow is resolved at a scale significantly finer than the particle size. This allows to capture pore-scale flow effects, particle rearrangements, and evolving soil resistance during installation, offering a higher level of detail compared to unresolved or continuum methods.
The modeling approach is used to explore how soil characteristics and installation parameters influence the development of piping erosion and the resulting installation performance. By systematically varying key parameters, conditions are identified that promote either stable penetration or the onset of piping erosion, highlighting the critical role of seepage near the skirt tip. Beyond identifying failure envelopes, the simulations provide micromechanical insight into how local forces, flow paths, and soil resistance evolve as erosion initiates and progresses. These insights enable the critical examination of common assumptions regarding resistance distribution inside and outside the bucket during suction-driven installation.
Additionally, the fully resolved simulation data can serve as a reference for calibrating and improving continuum-based models, bridging the gap between particle-scale mechanisms and engineering-scale predictive tools. The results illustrate how fully resolved LBM-DEM modeling can complement experimental and field studies, providing a powerful tool for developing more robust suction bucket installation strategies in challenging seabed conditions.

Mixed-Precision and Energy-Efficiency in SEM Codes
2026-06-24 15:45 - 17:15 (Europe/Paris) | Congress Center Hamburg, Congressplatz 1, Hamburg, 20355, Germany
If you’re going to be at ISC26 in Hamburg this year, take a break and visit our own Yanxiang Chen and his poster “Poster: Mixed-Precision and Energy-Efficiency in SEM Codes.”
Mixed-precision computing has emerged as a key strategy to improve performance and energy efficiency on current and future high-performance computing (HPC) systems. However, integrating mixed-precision into large, production-level scientific applications remains challenging due to concerns about numerical stability, accuracy, and the complexity of identifying which computations can safely tolerate reduced precision. In this work, we propose a systematic and practical methodology for enabling mixed-precision in spectral element codes by combining insights from computer arithmetic tools, performance modeling, and targeted algorithmic analysis.
Our approach leverages three complementary components: first, computer arithmetic tools, such as Verificarlo, to instrument and analyze floating-point behavior throughout an application; second, a roofline performance model to quantify the potential computational benefits of lower-precision arithmetic; and third, precision-aware numerical techniques to mitigate or eliminate instabilities introduced when reducing precision in critical algorithmic kernels. Together, these elements form a repeatable framework that guides developers in deciding where and how to apply mixed precision without compromising scientific correctness.
To demonstrate the effectiveness of our methodology, we apply it to two representative spectral element codes widely used in computational fluid dynamics (CFD): Nekbone and Neko. Nekbone is a mini-application proxy for the spectral element CFD code Nek5000, while Neko is a modern spectral element code used for solving incompressible Navier–Stokes equations. For each code, we perform a detailed precision analysis, identify precision-sensitive and precision-robust regions, and design mixed-precision variants accordingly.
In the Nekbone case study, our analysis reveals that mixed precision can significantly accelerate the Conjugate Gradient (CG) solver without adversely affecting convergence or solution quality. We address stagnation phenomena often observed in reduced-precision CG by integrating arithmetic verification with adaptive precision controls, effectively preserving numerical stability. When executed on the MareNostrum 5 supercomputer, the mixed-precision Nekbone achieves a 1.62x speedup in time-to-solution and a 2.43x reduction in energy-to-solution relative to the double-precision baseline, demonstrating substantial gains in both performance and energy efficiency.
For the full Neko application, we extend our precision strategy to a broader set of computational kernels, leveraging the insights gained from Nekbone and applying them within the context of the momentum solver in the Navier-Stokes equation on the Poisson example. The mixed-precision Neko implementation attains up to ~1.3x improvement in both execution time and energy consumption compared to the double-precision version, while maintaining the solution accuracy.
These results confirm that mixed-precision approaches, when carefully designed and guided by arithmetic and performance analysis, can yield significant improvements on HPC platforms for real-world scientific applications. Our methodology provides a general blueprint for HPC developers to adopt mixed precision in other spectral element and iterative methods, ultimately contributing to more efficient utilization of future exascale systems.
