The Lattice Boltzmann Method (LBM) simulates fluid dynamics by tracking particle distribution functions on a discrete lattice. Instead of solving the Navier-Stokes equations directly, it models mesoscopic particle populations that collectively reproduce macroscopic fluid behavior.

• 1Collision — distributions relax toward equilibrium at rate 1/τ, where τ controls viscosity.
• 2Streaming — each distribution moves one lattice cell along its velocity direction (D2Q9: 9 directions).
• 3Bounce-back — distributions hitting solid barriers reverse direction, creating no-slip walls.

The Reynolds number Re = U·L / ν determines the flow regime. Low Re gives smooth laminar flow; higher values produce vortex shedding and turbulence. Try reducing viscosity with the Cylinder preset to see a von Kármán vortex street emerge.