Hi Matt, Thanks a lot for the suggestion. Yan
On Tue, Jan 26, 2010 at 5:46 AM, Matthew Knepley <knepley at gmail.com> wrote: > You might try the pseudo-transient continuation code. > > Matt > > > On Mon, Jan 25, 2010 at 9:03 PM, Ryan Yan <vyan2000 at gmail.com> wrote: > >> Hi All, >> Hopefully, this is not considered as an off-topic thread. Since I got snes >> converged reason -6. >> >> Can anyone please share some hints on how to find a good inital guess? >> >> I am solving a nonlinear BVP(steady-states) extracted from a >> time-dependent problem by setting d/dt=0. The equation is conservational law >> for mass, momentum, internal energy, with an algebraic heating source. After >> all, v(velocity), P(pressure), U(fluid internal energy), can be solved from >> this coupled system. I am using Newton's method for this nonlinear system. >> Frankly, I do not have a good initial guess for the solver. The only >> information that I have is the inital condition for the time-dependent >> problem, where the BVP comes from. I have tried my solver with different >> inital guess for many times, but with no luck of a satisfying residual >> reduction. >> >> So, do I have to solve the time-dependent problem after a long time >> stepping to get a steady solution? Or is there any better way of finding a >> good initial guess? >> >> Any suggestion is highly appreciated. >> >> Yan >> > > > > -- > 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 > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20100126/f0cf6314/attachment.htm>