It is possible the information provided by the discrete adjoint here is somewhat less meaningful, but I need to analyze them for off-design conditions for optimizations. I am using a centered discretrization plus scalar JST dissipation. I have not tried using LU on the subdomains, that is certainly something to try.
Thank you for your help, Gaetan On Mon, Apr 29, 2013 at 10:51 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote: > Gaetan Kenway <gaetank at gmail.com> writes: > > > It is an SA turbulence model and the discrete adjoint computed exactly > with > > AD. Certainly the grids are highly stretched in the BL since the grids > are > > resolving the viscous sublayer (y+ < 1) and the Reynolds numbers are on > > the order of 10's of millions. I tend only to see this behaviour at > > higher mach numbers when stronger shocks start to appear. For example, > the > > adjoint system may solve fine at M=0.80, and fail to converge at > M=0.85. > > How meaningful is the information provided by the discrete adjoint here? > Limiters and even just upwind discretizations on non-uniform grids lead > to inconsistent discretizations of the adjoint equations. If the > adjoint equation is full of numerical artifacts, it can cause the linear > problem to lose structure, resulting in singular sub-problems, negative > pivots, and other badness. What happens when you use a direct solve for > subdomain problems (ASM+LU; use smaller subdomains if necessary)? > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20130429/44b85103/attachment.html>
