The Fluid Simulator That Doesn’t Solve the Fluid Equations

The Lattice Boltzmann Method (LBM) simulates fluid dynamics by modeling the statistical behavior of particle collections, rather than solving the complex Navier-Stokes equations directly. Its core algorithm alternates between a local "collision" step, where particle distributions relax toward equilibrium, and a "streaming" step where they propagate to neighboring grid points. A single parameter, the relaxation time, elegantly controls the fluid's viscosity by dictating how quickly the system returns to equilibrium. This method's structure is inherently local, making it "embarrassingly parallel" for high performance and allowing it to handle complex geometries with simple rules, avoiding difficult mesh generation.