Euler-Lagrange multiphase flow simulations in the GPU-accelerated spectral element solver NekRS*

Direct and Large Eddy Simulations using coupled Euler-Lagrange approaches

are commonly used to study complex multiphase flows.  Applications of such

simulations range from the spread of airborne droplets and aerosols as

potential virus carriers to detailed cloud-droplet dynamics.  The particle

simulation library, PPICLF [1,2], which includes state-of-the-art four-way

particle/droplet coupling already exists for spectral elements in a CPU-based

framework.  Such strong support, however, is not yet found in a GPU-based

framework.  This work aims to provide a plug-in to the GPU-based spectral

element fluid flow solver, NekRS, to incorporate interactions of Lagrangian

particles with fluid, other particles, and boundaries of the domain. The solver

also includes the interaction forces exerted by the particles back onto the

fluid. These capabilities are used to simulate cloud-droplet growth

by condensation in turbulent flows. Using this example, we evaluate the impact

of each component of the plug-in on the parallel GPU performance.

[1] Zwick, D., ppiclF: A parallel particle-in-cell library in Fortran,

J. Open Source Software, May 2019.

[2] Zwick, D. (2019). Scalable highly-resolved Euler-Lagrange multiphase flow simulation with

applications to shock tubes. (Doctoral dissertation). University of Florida.