Pushing the cell Péclet number to 2 drove the solution to -0.33 — where the energy to minimize disappeared
·8 min read
Advection skews the stiffness matrix, so the energy minimum is gone. At cell Péclet 2, Galerkin falls to -0.33; SUPG buys a bound, not symmetry.
Raise the Velocity, Lose 27% of Your Diffusion — The Extra Flux in LBM Convection-Diffusion
·7 min read
Set D through tau in a lattice Boltzmann convection-diffusion model and it still spreads at D(1-u²/cs²). Where Chapman-Enskog drops the extra flux, and the source term that erases it.