Minisymposium Presentation

Particle-particle particle-mesh (PPPM) methods are used to describe advective dynamics (represented by particle discretizations) that are coupled to nonlocal fields (represented by grid discretizations). Our objective is to implement one such method, the Method of Local Corrections (MLC) for vorticity transport in 3D, on GPUs using performance-portable libraries: Cabana for particles, and FFTX for FFT-based solutions to the field equations. MLC splits the calculation of the velocity field into two parts: near-field (local N-body calculations) and far-field (single free-space convolution). MLC exercises the full capabilities and data choreography of Cabana where local N-body calculations and grid to / from particle interpolations are accelerated. FFTX is needed for the free space convolution step to approximate the velocity on the grid. Using this MLC method, we also develop more a systematic numerical analysis for particle methods in 3D via numerical experiments. Particles deforming significantly from the initial grid locations leads to large interpolation errors which leads to velocity errors and “particle noise". We address this with adaptive remapping where we map particles back to a Eulerian grid selectively, in regions where the particle locations have undergone large deformations.