> > Both approximations are in the preconditioner. > > > I'm afraid I don't have an explanation based on the information you have > sent. If you can set up a test case that shows the issue, I'll investigate > further.
Thanks for offering, unfortunately I don't have a small testcase that shows the same behaviour. It only happens in the odd industrial case, convergence is fine for most similar cases and perfect for small academic cases. > > I would think about null space issues. For example, if the Schur complement > has constants in its null space, but the right hand side is not consistent > and/or the KSP was not informed of the null space. Definitely not the constant, but there could be a near null space... dr. ir. Christiaan Klaij CFD Researcher Research & Development E mailto:C.Klaij at marin.nl T +31 317 49 33 44 MARIN 2, Haagsteeg, P.O. Box 28, 6700 AA Wageningen, The Netherlands T +31 317 49 39 11, F +31 317 49 32 45, I www.marin.nl
