Neko: A Modern, Portable, and Scalable Framework for Extreme-Scale Computational Fluid Dynamics

Join our own Niclas Jansson at the SIAM Conference on Computational Science and Engineering (CSE25) in Fort Worth, Texas, for his talk “Neko: A Modern, Portable, and Scalable Framework for Extreme-Scale Computational Fluid Dynamics” in the mini-symposium MS19: Performance Benchmarking of Scientific Libraries and Applications.

Recent trends and advancements in utilizing more diverse and heterogeneous hardware in High-Performance Computing (HPC) are challenging scientific software developers in their pursuit of efficient numerical methods with sustained performance across a diverse set of platforms. As a result, researchers are bing forced to refactor their codes to leverage these powerful new heterogeneous systems. We present our work on addressing the extreme-scale computing challenges in computational fluid dynamics, ensuring exascale readiness of turbulence simulations. Focusing on Neko, a high-fidelity spectral element code, 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.