FLEKS — FLexible Exascale Kinetic Simulator

FLEKS is a highly-optimized Particle-In-Cell (PIC) and particle tracker code built on top of the AMReX block-structured adaptive mesh refinement framework.

It natively serves as the PC (Particle-in-Cell) and PT (Particle Tracker) components within the SWMF (Space Weather Modeling Framework), heavily coupling with BATS-R-US via the MHD-AEPIC algorithm to provide hybrid kinetic resolution to global MHD models.

Primary Capabilities

• Implicit PIC: Semi-implicit $\theta$-scheme solvers leveraging AMReX GMRES and heavily optimized particle-push boundaries.
• Particle Tracking: Massively parallel test particle tracking in turbulent MHD and PIC electromagnetic fields.
• MHD-AEPIC: True bi-directional coupling between global space weather MHD states and sub-grid PIC regimes.
• Adaptive Tracing: Utilizes AMReX regridding and dynamic load balancing.

Build Requirements

FLEKS is designed to be built continuously alongside SWMF. See the SWMF documentation for environment requirements.

• CMake (Optional, for standalone builds)
• C++14/17 compatible compiler (e.g., g++ 8+, clang++ 9+, or icpc)
• Fortran 90 compiler (e.g., gfortran, ifort for srcInterface/)
• MPI (MPICH or OpenMPI)

Quick Start (via SWMF)

To compile the library and the SWMF integrated test scenario:

# Inside the SWMF root directory
make test16_3d_compile
make test16_3d

Documentation

• Algorithms & Physics: Please see docs/Algorithm.tex for the mathematical foundations of the simulation engine.
• Component Architecture: Every core directory contains an extensive AGENT.md file describing layout, file purposing, and structure.
• Coding Standards & Contributing: See CONTRIBUTING.md before making a pull request.

Data Processing

All outputs from FLEKS natively stream to AMReX block formats. Do not use generic NetCDF loaders. Please leverage the Python flekspy API via:

pip install flekspy

License

Apache 2.0 (University of Michigan)