“Scalable High-Fidelity Simulation of Turbulence With Neko Using Accelerators” CUG 2023 “Sustainable Exascale”

CSCT Center for Science Ltd (CSC Finland) Helsinki, Finland

It’s time again for the annual Cray User Group (CUG) conference: this time in Finland! We’ll be contributing to the discussions on how to best use Cray and HPE supercomputers with a paper titled, “Scalable High-Fidelity Simulation of Turbulence With Neko Using Accelerators”. You will also be able to read the paper on our publication page after the conference.

Neko: A Modern, Portable, and Scalable Framework for High-Fidelity Computational Fluid Dynamics

Recent trends and advancements including more diverse and heterogeneous hardware in High-Performance Computing are challenging scientific software developers in their pursuit of good performance and efficient numerical methods. As a result, the well-known maxim “software outlives hardware” may no longer necessarily hold true, and researchers are today forced to re-factor their codes to leverage these powerful new heterogeneous systems. We present Neko – a portable framework for high-fidelity spectral element flow simulations. Unlike prior works, Neko adopts a modern object-oriented Fortran 2008 approach, allowing multi-tier abstractions of the solver stack and facilitating various hardware backends ranging from general-purpose processors, accelerators down to exotic vector processors and Field-Programmable Gate Arrays (FPGAs) via Neko’s device abstraction layer. Focusing on the performance and accuracy of Neko, we show the first direct numerical simulation (DNS) of a Flettner rotor submerged in a turbulent boundary layer, observing excellent agreement of lift with experimental data. Using a mesh with five million spectral elements, which turns into more than a billion unique degrees of freedom, the simulation requires less than three days to complete on accelerated systems compared to weeks on traditional non-accelerated systems. Finally, we present performance measurements on a wide range of accelerated computing platforms, including the EuroHPC pre-exascale system LUMI, where Neko achieves excellent parallel efficiency for a large DNS of turbulent fluid flow using up to 80% of the entire LUMI supercomputer.

Sustainable and Reliable Computing with Tools: Analyzing Precision Appetites of CFD Applications with VerifiCarlo

Energy consumption constraints for large-scale computing encourage scientists to revise the architecture design of hardware but also applications, algorithms, as well as the underlying working/ storage precision. I will introduce an approach to address the issue of sustainable, but still reliable, computations from the perspective of computer arithmetic tools. We employ VerifiCarlo and its variable precision backend to identify the parts of the code that benefit from smaller floating-point formats. Finally, we show preliminary results on proxies of CFD applications.

Code of the Month vol.6 “Neko by CEEC” — PUBLIC event

Online

Recent trends and advancements including more diverse and heterogeneous hardware in High-Performance Computing are challenging scientific software developers in their pursuit of good performance and efficient numerical methods. As a result, the well-known maxim “software outlives hardware” may no longer necessarily hold true, and researchers are today forced to re-factor their codes to leverage these powerful new heterogeneous systems. We present Neko – a portable framework for high-fidelity spectral element flow simulations. Unlike prior works, Neko adopts a modern object-oriented Fortran 2008 approach, allowing multi-tier abstractions of the solver stack and facilitating various hard- ware backends ranging from general-purpose processors, accelerators down to exotic vector processors and Field Programmable Gate Arrays (FPGAs) via Neko’s device abstraction layer. Focusing on Neko’s performance and exascale readiness, we outline the optimisation and algorithmic work necessary to ensure scalability and performance portability across a wide range of platforms. Finally, we present performance measurements on a wide range of accelerated computing platforms, including the EuroHPC pre-exascale systems LUMI and Leonardo, where Neko achieves excellent parallel efficiency for an extreme-scale direct numerical simulation (DNS) of turbulent thermal convection using up to 80% of the entire LUMI supercomputer.

CEEC at the Euro HPC Summit Poster Session

Flanders Meeting and Convention Centre, A Room with a ZOO Koningin Astridplein 20-26, Antwerp, Belgium

If you’re interested in our progress over the last year or hoping to ask us questions about our plans for the future, don’t miss the chance to talk with our own Niclas Jansson at the first poster session of the Euro HPC Summit on Tuesday, March 19th!

Neko: A modern, Portable, and Scalable Framework for High-Fidelity Computational Fluid Dynamics

Lisbon Congress Centre Praça das Indústrias 1, Lisboa, Portugal

If you’ll be at ECCOMAS 2024, check out ‘Neko: A modern, Portable, and Scalable Framework for High-Fidelity Computational Fluid Dynamics’ presented by Niclas Jansson on the terrace.CEEC will have a robust presence at ECCOMAS24 this summer in Lisbon, Portugal! Over the course of the conference, we will be represented in three mini-simposium talks ranging from progress with our wind turbine lighthouse case to our latest work on improving FLEXI.