Hi
Thanks for your reply. I have attached the code and I would appreciate if you could run it once and see if you can sopt the problem.
Hatef
Anders Logg wrote:
On Mon, Jan 19, 2009 at 10:38:16PM -0500, Hatef Monajemi wrote: > > Hi, > > > > Yes, You are right. I am interested in a problem similar to Navier-Stokes but > > not exactly that. > > > > I took a look at Unicorn, Although it was not updated, I figured out how the > > solver was written based on Fixed Point iterations. > > > > My question referes to dolfin VariationalProblem.cpp at line 75: > > > > "void VariationalProblem::solve(Function& u0, Function& u1)" > > > > This means that one should be able to solve the nonlinear problems with more > > than one variable by just augmenting the state-space vector and solving the > > whole state with Newton's iteration. > Yes, that should be possible in principle, but there's no guarantee > that it will always converge. > > The only difference with the linear case should be the fact that > > instead of solving for the solution (U) dirrectly, the nonlinear > > problem should be sovled for an increment (\delta U) around a > > guessed solution (say U0) and correcting the U0 in every Newton's > > iteration. > Yes. > > To me it should be possible to solve a nonlinear problem with Newton's > > iteration based on what I can see in the afforementioned file in (dolfin/fem) > > .Please correct me if I am wrong. However the following peice of code gives an > > error like "Missing eval() for user-defined function (must be overloaded)". and > > in my usr-define functions such as Source, etc eval() is overloaded. I do not > > see where the problem arises. Any opinion? > > > > {VariationalProblem nlpde(a,L,bcs,true); > > nlpde.solve(U,P);} > Could you send the rest of the code as well (the form files). I won't > have time to debug your code but I can try running it once to see if I > can spot the problem. > -- > Anders > > > > > > Thanks > > > > Hatef > > > > > > > > >Hi Hatef, > > > > >It sounds as if you are interested in the Navier-Stokes equations, or > > > > >similar? If so, you may want to check out the Unicorn solver: > > > > >http://www.fenics.org/wiki/Unicorn > > > > >Direct any Unicorn questions to: [email protected] > > > > > >Best, > > >Johan > > > > _______________________________________________ > > DOLFIN-dev mailing list > > [email protected] > > http://www.fenics.org/mailman/listinfo/dolfin-dev >
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