On Fri, May 15, 2015 at 4:43 PM, Sanjay Kharche < [email protected]> wrote:
> > Dear All > > When I put in my convection terms, my solution is not well behaved. > Following is an elaboration. I am wondering if I missed something in Petsc. > > I am solving the 3D heat equation with convection terms using second order > finite differences and the boundary conditions are 1st order. It is solved > on an uneven geometry defined inside a box, where a voltage variable > diffuses. I am using a ts solver. The 3D DMDA vector uses a star stencil (I > have also tried the box stencil). I assign the RHS at FD nodes where there > is geometry. I get a stable solution if I do not have convection terms. > However, when I use the convection terms, an error seems to build up. > Eventually, the non-geometry part of the box also starts having a non-zero > voltage. I checked my FD scheme for errors in terms. I also tested it out > on a non-petsc explicit solver. The scheme is correctly written in the RHS > function. The explicit solver is stable for the integration parameters I am > using. Can you suggest what could be missing in terms of Petsc or otherwise? > Use the Method of Manufactured Solutions to check your residual function. Matt > cheers > Sanjay > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
