mixing elbow simulation OpenFOAM

[spacefun]

Hi all,
I'm trying to solve a simulation of mixing elbow with OpenFOAM.
I used the classical configuration of elbow template found on tutorial folder of OpenFoam.
When I launched simulation it crashes after increasing time and I got this:

Time = 0.25

Courant Number mean: 2436.58 max: 20540.4
smoothSolver:  Solving for Ux, Initial residual = 0.868476, Final residual = 6.33673e+188, No Iterations 1000
smoothSolver:  Solving for Uy, Initial residual = 0.796671, Final residual = 4.37419e+189, No Iterations 1000
smoothSolver:  Solving for Uz, Initial residual = 0.797959, Final residual = 1.21762e+189, No Iterations 1000
#0  Foam::error::printStack(Foam::Ostream&) at ??:?
#1  Foam::sigFpe::sigHandler(int) at ??:?
#2   in "/lib/x86_64-linux-gnu/libc.so.6"
#3  double Foam::sumProd<double>(Foam::UList<double> const&, Foam::UList<double> const&) at ??:?
#4  Foam::PCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:?
#5  Foam::fvMatrix<double>::solveSegregated(Foam::dictionary const&) at ??:?
#6  Foam::fvMatrix<double>::solve(Foam::dictionary const&) at ??:?
#7  
 at ??:?
#8  
 at ??:?
#9  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#10  
 at ??:?

I changed the boundary conditions getting a change in times, but never I got a complete result.
Could someone help me?

Thanks

 

[MikeHalloran]

Your solver appears to be diverging, rapidly, not converging.

Can you stop it after just a few iterations, before it really goes off into the weeds? Maybe then you can make sense of what's happening.


Mike Halloran
Pembroke Pines, FL, USA

 

[spacefun]

You're right, but I reduced at the minimum the inlet speed but I didn't find a convergence.
Actually I don't understand what are the equations at the base of this solver.
Could you explain me?

 

[MikeHalloran]

I wish I could. The latest OpenFOAM only runs on 64 bit machines, and I don't have one. ... and I wasn't that good with earlier versions, either.

What you seem to have there is just a bunch of error messages, all pretty much indicating that a lot has gone wrong.
For instance, at 1000 iterations, the residuals have all gone to xx.xe^189 or so. ... which I suspect is a number range limit somewhere. It's certainly too big a number for a residual, or for pretty much anything in our universe.

Computers do strange things when you bang them up against really big numbers like that. ... so the first error message is most likely the only one that's truly valid.

Subsequent messages just mean that the computer "has gone off to see God".

Try setting the number of iterations to 100, or 10, or 3, and see what errors you get then.


Mike Halloran
Pembroke Pines, FL, USA