cm_lbm: Introduction

This project implements a lattice Boltzmann fluid solver with the central moments multiple relaxation time collision operator (CM-MRT). It was my final project for computer graphics (CSE528). The core applications is written in rust and targets WGPU compute shaders. It generates VTK files that can be post-processed in Paraview. In addition, python is used for code-generation.

Contents

sympy_codegen

This directory contains a python script codegen.py and supporting modules to generate shader code for several kernels needed by LBM. The operations are represented symbolically using SymPy. In particular, checkout the sympy_codegen/gen_*.py files, there's one for each operation.

cm_lbm_generated

This is a rust crate that strictly contains the generated operators. There are two to three versions of each operator. In cm_lbm_generated/src/shader_ops we have rust functions that contains a WGSL function as a string which will get templated into a shader at runtime. cm_lbm_generates/src/rust_ops contains the operators single and maybe double-precision rust functions.

cm_lbm

This contains the actual runtime library needed to run a simulation. cm_lbm/examples that contains several applications that hardcode different simulations and generate the figures for my report. cm_lbm/examples/example_1.rs would be a good place to start exploring the code base. cm_lbm/src/solver/solver_state.rs defines the solver state and its various operations.

Commands

Code Generation

The generated functions are checked into git, but to re-generated them run the following:

python sympy_codegen/codegen.py

Run Example 1

The header image was generated with example_1.rs. This can be run with

cargo run --release --example example_1 -- --output-dir <dir-for-output-files>

Note that this example will generate over 300gb of data.