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JustPIC.jl

Particle-in-Cell (PIC) advection for large-scale, multi-XPU simulations. JustPIC runs the same code on CPU, CUDA, AMDGPU, and Metal through KernelAbstractions: the compute backend is chosen by the array type, not by rewriting the algorithm.

Installation

JustPIC is registered in the General registry:

using Pkg
Pkg.add("JustPIC")

To run on a GPU, additionally install the matching backend package (CUDA, AMDGPU, or Metal) and select its backend — see Mixed CPU/GPU.

Getting started

Choose a backend, build a staggered grid, and initialize a particle container:

julia> using JustPIC

julia> backend = JustPIC.CPU;

julia> nxcell, max_xcell, min_xcell = 6, 12, 3;

julia> n = 8;  # vertices per dimension

julia> xv = yv = LinRange(0.0, 1.0, n);

julia> dx = dy = xv[2] - xv[1];

julia> xc = yc = LinRange(dx / 2, 1 - dx / 2, n - 1);

julia> grid_vx = xv, LinRange(first(yc) - dy, last(yc) + dy, length(yc) + 2);

julia> grid_vy = LinRange(first(xc) - dx, last(xc) + dx, length(xc) + 2), yv;

julia> particles = init_particles(backend, nxcell, max_xcell, min_xcell, grid_vx, grid_vy);

julia> sum(particles.index.data)  # number of active markers across the grid
392

particles can then be advected through a velocity field and used for grid-to-particle and particle-to-grid interpolation. See Particles and Interpolations for the full workflow, or the runnable 2D field advection example.

Manual

Funding

The development of this package is supported by the GPU4GEO PASC project.