[Getdp] ... Formulation question ...
Matt Koch
mattkoch at scitex.us
Mon Mar 5 02:56:31 CET 2007
Hello Olivier,
thank you very much for the feedback! I think we are getting somewhere
now! So, basically, we make Phi a Dof by saying so in the first Galerkin
term, and then we use it without Dof in the second Galerkin term. I
guess, as you say, that makes Phi explicit, so let's hope this scheme is
stable. I assume this also means that in the second Galerkin term, the
Phi from the previous time step is used? I'll start playing with this
again sometime early this week. Also, I think my second equation can now
be solved in a very similar way, presuming I can come up with the signum
function, and presuming I can embed a TimeLoopTheta in a TimeLoopTheta,
perhaps like so:
Resolution {
{Name ResTraNonLin;
System {
{Name Sys1; NameOfFormulation Frm1;}
{Name Sys2; NameOfFormulation Frm2;}
}
Operation {
InitSolution[Sys1];
SaveSolution[Sys1];
TimeLoopTheta[Tme1Zro,Tme1Drn,Tme1Stp,Tme1Scm] {
IterativeLoop[Itn1Cnt,Itn1Eps,Itn1Rlx] {
GenerateJac[Sys1];
SolveJac[Sys1];
}
Test[SveFct[]] {SaveSolution[Sys1];}
Test[RstFct[]] {
"TransferSolution from Sys1 to Sys2"
TimeLoopTheta[Tme2Zro,Tme2Drn,Tme2Stp,Tme2Scm] {
IterativeLoop[Itn2Cnt,Itn2Eps,Itn2Rlx] {
GenerateJac[Sys2];
SolveJac[Sys2];
}
"TransferSolution from Sys2 to Sys1"
}
}
}
}
}
Any thoughts on this construct? I am not sure how the transfer of
solutions can be done, though. And yes, most naturally I would write
this up for general GetDP use if it ends up working.
Thanks and Regards,
Matt Koch
Olivier Castany wrote:
> Hello,
>
> now that you give a more precise desciption of your problem, I
> understand that you want to solve a dynamic equation.
>
> I can only be of little help since I do not understand the part b) of
> the algorithm you want to program.
>
> I can just say that it is possible to program the equation :
>
>
>> a) d/dt(Phi) + Spd*Norm(Grad(Phi)) = 0
>>
>
> the formulation would be :
>
> Galerkin { Dt [ Dof{Phi} , {Phi} ] ; ... }
> Galerkin { [ Spd[] * Norm[{d Phi}] , {Phi} ] ; ... }
>
> and the resolution with "TimeLoopTheta" will be an explicit Euler
> algorithm.
>
> As I don't really understand your algorithm with b), I can't say if it
> is possible to do it with GetDP. My feeling is that it is not currently
> possible without modifying the program.
>
> Regards,
>
> O.C.
>
> PS : if you manage to do something nice with the level set equations,
> maybe you can post it later or put it on the wiki ?
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