pisoFoam - Too high Courant Numbers
 

Hi all,

I want to simulate a 3d case where a flow in a channel with a square cross section passes a barrier. See the sketch below.

https://www.dropbox.com/s/47q8bwl6xf...metry.png?dl=0http://s11.postimg.org/ylijf9kvn/geometry.png

It's my very first case after going through the tutorials :)

So, I decided to use pisoFoam since I believe it's well suitable for my case.
My problem is that I get incredible high Courant numbers so that my calculation crashes.

I've put some info for you. I hope you guys can help me :confused:

fvSolution:
https://dl.dropboxusercontent.com/u/59780963/fvSolution

fvSchemes:
https://dl.dropboxusercontent.com/u/59780963/fvSchemes

checkMesh:
https://dl.dropboxusercontent.com/u/59780963/checkMesh

And that's the error I get:
Time = 0.025

Courant Number mean: 3.03546e+85 max: 1.06297e+89
smoothSolver: Solving for Uy, Initial residual = 1, Final residual = 1.44087e-15, No Iterations 1
#0 Foam::error::printStack(Foam::Ostream&) at ??:?
#1 Foam::sigFpe::sigHandler(int) at ??:?
#2 in "/lib/x86_64-linux-gnu/libc.so.6"
#3 Foam::GAMGSolver::scale(Foam::Field<double>&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, Foam::Field<double> const&, unsigned char) const at ??:?
#4 Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMa trix::smoother> const&, Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const at ??:?
#5 Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:?
#6 Foam::fvMatrix<double>::solveSegregated(Foam::dict ionary const&) at ??:?
#7 Foam::fvMatrix<double>::solve(Foam::dictionary const&) at ??:?
#8 Foam::fvMatrix<double>::solve() at ??:?
#9
at ??:?
#10 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#11
at ??:?
Floating point exception (core dumped)

Hey,

The easiest option is to use pimpleFoam where you can set the maximum courant number.

If you want use pisoFoam, you need to reduce the time step (delta t) in order to reduce the courant number.

Kind Regards,
Hasan K.J