Large-Scale Direct Numerical Simulations of Turbulence Using GPUs and Modern Fortran

TL;DR

This paper demonstrates scalable direct numerical simulations of turbulence on modern supercomputers using Fortran and GPUs, including the first simulation of flow around a Flettner rotor at high Reynolds number.

Contribution

It introduces a GPU-accelerated spectral element method implementation in Fortran for large-scale turbulence simulations, including the first simulation of a Flettner rotor at Re=30,000.

Findings

First DNS of flow around a Flettner rotor at Re=30,000.

AMD MI250X GPU performance comparable to two Nvidia A100 GPUs.

Similar power efficiency between MI250X and A100 GPUs.

Abstract

We present our approach to making direct numerical simulations of turbulence with applications in sustainable shipping. We use modern Fortran and the spectral element method to leverage and scale on supercomputers powered by the Nvidia A100 and the recent AMD Instinct MI250X GPUs, while still providing support for user software developed in Fortran. We demonstrate the efficiency of our approach by performing the world's first direct numerical simulation of the flow around a Flettner rotor at Re=30'000 and its interaction with a turbulent boundary layer. We present one of the first performance comparisons between the AMD Instinct MI250X and Nvidia A100 GPUs for scalable computational fluid dynamics. Our results show that one MI250X offers performance on par with two A100 GPUs and has a similar power efficiency.