STREAmS: a high-fidelity accelerated solver for direct numerical simulation of compressible turbulent flow

We present STREAmS, an in-house high-fidelity solver for large-scale, massively parallel direct numerical simulations (DNS) of compressible turbulent flows on graphical processing units (GPUs). STREAmS is written in the Fortran 90 language and it is tailored to carry out DNS of canonical compressible wall-bounded flows, namely turbulent plane channel, zero-pressure gradient turbulent boundary layer and supersonic oblique shock-wave/boundary layer interactions. The solver incorporates state-of-the-art numerical algorithms, specifically designed to cope with the challenging problems associated with the solution of high-speed turbulent flows and can be used across a wide range of Mach numbers, extending from the low subsonic up to the hypersonic regime. The use of cuf automatic kernels allowed an easy and efficient porting on the GPU architecture minimizing the changes to the original CPU code, which is also maintained. We discuss a memory allocation strategy based on duplicated arrays for host and device which carefully minimizes the memory usage making the solver suitable for large scale computations on the latest GPU cards. Comparison between different CPUs and GPUs architectures strongly favor the latter, and executing the solver on a single NVIDIA Tesla P100 corresponds to using approximately 330 Intel Knights Landing CPU cores. STREAmS shows very good strong scalability and essentially ideal weak scalability up to 2048 GPUs, paving the way to simulations in the genuine high-Reynolds number regime, possibly at friction Reynolds number $Re_{\tau} > 10^4$. The solver is released open source under GPLv3 license and is available at https://github.com/matteobernardini/STREAmS.