A portable OpenCL-based unstructured edge-based finite element Navier–Stokes solver on graphics hardware

•Unstructured Navier–Stokes solver written in OpenCL.•Addressing code and performance portability.•A new multi-line vectorization strategy for the SpMV algorithm.•Adaptively choosing the optimal settings by running an optimization step.•Good speedup for real examples against a fully optimized parallel OpenMP solver.

The rise of GPUs in modern high-performance systems increases the interest in porting portion of codes to such hardware. The current paper aims to explore the performance of a portable state-of-the-art FE solver on GPU accelerators. Performance evaluation is done by comparing with an existing highly-optimized OpenMP version of the solver. Code portability is ensured by writing the program using the OpenCL 1.1 specifications, while performance portability is sought through an optimization step performed at the beginning of the calculations to find out the optimal parameter set for the solver. The results show that the new implementation can be several times faster than the OpenMP version.