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. 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.
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);}
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
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