Lattice Boltzmann vs. Darcy flow for capillary tendrils

Lattice Boltzmann provides incredible fluid mechanics, but it devours memory bandwidth on Apple Silicon. I set up an A/B test in a 696-line FluidBleedExperiment.ts harness to compare an LBM D2Q9 model against an anisotropic Darcy tensor for simulating the lush capillary tendrils (Hige-nijimi) of watercolor bleed. While LBM is mathematically elegant, it bottlenecked the unified memory architecture. We pivoted to a 2-layer Darcy porous flow with saturation gating—yielding a stable WebGPU compute pipeline that visually matches the organic wicking without the performance penalty.