  We propose a highly versatile computational framework for the simulation of
cellular blood flow focusing on extreme performance without compromising
accuracy or complexity. The tool couples the lattice Boltzmann solver Palabos
for the simulation of the blood plasma, a novel finite element method (FEM)
solver for the resolution of the deformable blood cells, and an immersed
boundary method for the coupling of the two phases. The design of the tool
supports hybrid CPU-GPU executions (fluid, fluid-solid interaction on CPUs, the
FEM solver on GPUs), and is non-intrusive, as each of the three components can
be replaced in a modular way. The FEM-based kernel for solid dynamics
outperforms other FEM solvers and its performance is comparable to the
state-of-the-art mass-spring systems. We perform an exhaustive performance
analysis on Piz Daint at the Swiss National Supercomputing Centre and provide
case studies focused on platelet transport. The tests show that this versatile
framework combines unprecedented accuracy with massive performance, rendering
it suitable for the upcoming exascale architectures.
