A 1% Error in Diameter Is a 4% Error in Flow Rate — Half a Cell of Wall and Poiseuille's Constant
·7 min read
Pipe flow rate rides on the fourth power of the diameter. The same exponent explains a mesh with the wall half a cell off and Poiseuille's 1838 glass tubes.
Three at a wall, five at a corner — counting the populations an LBM boundary node loses
·7 min read
After streaming, the number of empty populations at a lattice-Boltzmann node equals the number of 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
·5 min read
The bounce rule that builds a no-slip wall, and where that wall really sits
How to Make an Outflow Stop Reflecting Sound — Navier–Stokes Characteristic Boundary Conditions
·5 min read
The single most common cause of compressible-solver blow-ups, tamed by one parameter σ