I'm trying to implement the scheme he describes on his book "Computational Fluid Mechanics and Heat Transfer" on Chap.9 and I'm having trouble imposing BC.
I don’t get how he imposes them. I get up to the point where, following the Beam and Warming scheme and after linearizing each flux vector with the flux vector U, he gets to solve a linear system of a tridiagonal matrix with block matrixes inside (A, B,and C he calls them).
I understand the BC must be imposed on the first and last 5 rows of that matrix (1 for each variable of the flux vector). The problem is, if that linear system is written with the deltaU vector, the BC conditions must be imposed on the deltaU variables, and I don't know how.
I've already tried some approaches on my code, but none of them seem to work, as the Boundary Conditions I'm imposing always seem to oscillate.