27 of 1,681 Voxels Flipped Inside Out — Ray Parity and Link Cutting in STL Voxelization
·11 min read
Turning an STL into an LBM voxel grid takes four stages: octree culling, SAT overlap tests, ray parity, and the per-link cut fraction q, verified in code.
Three at a wall, five at a corner — counting the populations an LBM boundary node loses
·8 min read
After streaming, empty populations at an LBM node equal the solid cells around it: three on a flat wall, five in a concave corner, one on a convex corner.
In Lattice Boltzmann, the Wall Isn't on the Node — Bounce-Back and Zou-He Boundaries
·6 min read
Half-way bounce-back puts the wall a half-cell off the node. Couette speed is U(j+1/2)/ny. Height ny-1 leaves friction bias that refinement never clears.