At acoustic CFL 10 the preconditioner multiplied the error by 100 every sweep — the one arrow a block preconditioner throws away
·8 min read
Block Gauss-Seidel discards a pressure-velocity feedback whose gain is exactly the acoustic CFL squared. A 1D acoustic model measures the cost.
Where Jacobi Dies on a Boundary-Layer Mesh — the Linelet Line-Implicit Preconditioner
·7 min read
Why squashing cells toward the wall stalls point smoothers, and the fix
Solving Without Inverting the Matrix — GMRES and the Arnoldi Subspace
·6 min read
Building GMRES from scratch to solve sparse linear systems via Krylov and Arnoldi