  The Smoothed Particles Hydrodynamics (SPH) is a particle-based, meshfree,
Lagrangian method used to simulate multidimensional fluids with arbitrary
geometries, most commonly employed in astrophysics, cosmology, and
computational fluid-dynamics (CFD). It is expected that these
computationally-demanding numerical simulations will significantly benefit from
the up-and-coming Exascale computing infrastructures, that will perform 10 18
FLOP/s. In this work, we review the status of a novel SPH-EXA mini-app, which
is the result of an interdisciplinary co-design project between the fields of
astrophysics, fluid dynamics and computer science, whose goal is to enable SPH
simulations to run on Exascale systems. The SPH-EXA mini-app merges the main
characteristics of three state-of-the-art parent SPH codes (namely ChaNGa,
SPH-flow, SPHYNX) with state-of-the-art (parallel) programming, optimization,
and parallelization methods. The proposed SPH-EXA mini-app is a C++14
lightweight and flexible header-only code with no external software
dependencies. Parallelism is expressed via multiple programming models, which
can be chosen at compilation time with or without accelerator support, for a
hybrid process+thread+accelerator configuration. Strong and weak-scaling
experiments on a production supercomputer show that the SPH-EXA mini-app can be
efficiently executed with up 267 million particles and up to 65 billion
particles in total on 2,048 hybrid CPU-GPU nodes.
