CFDEM Compressible

Submitted by sviets on Thu, 03/01/2012 - 11:13

Hi,

I'm trying to build a Solver for a compressible fluid and everything works fine up to the point where the dragforce model DiFelice is called. To get some debug informations I inserted an Info-line to get the values at this point.

The error is a floating point exception, caused by a value of 6.9e-310 of nufField , than I tried to get values of the variables from which nufField is calculated, but there I can't find any mistake.

I hope anybody of you knows where the mistake is and could help me,
thanks for your help.

Attached the code of DiFelice and the log-file.

cgoniva's picture

cgoniva | Tue, 03/27/2012 - 14:22

Hi,

the attachement seems not to work...

concerning your question, this is not necessarily a bug in the coupling.
In the drag law there is a division by nuf e.g in Rep=u*d/nuf which gives an error for nuf=1e-310.

As nuf is calculated by your solver (at least I guess so?) this value close to zero might occur when the simulation crashes.

You could check the previous timesteps and see why the simulation blows up?

Cheers,
Chris

run_cfd | Fri, 09/27/2013 - 06:18

I was trying to establish coupling between sonicFoam and LIGGGHTS by mimicing the similar way as done in cfdemSolverPiso.
The following equations I fromed to be solved...
volScalarField voidfractionRho = voidfraction*rho;
\\continuity
solve(fvm::ddt(voidfractionRho) + fvc::div(phi)); \\phi is defined in createFields.H as "linearInterpolate(rho*U*voidfraction) & mesh.Sf()"

rho = voidfractionRho/voidfraction;
\\momentum
fvVectorMatrix UEqn
(
fvm::ddt(voidfractionRho, U)
+ fvm::div(phi, U)
+ turbulence->divDevRhoReff(U)
+ particleCloud.divVoidfractionTau(U, voidfraction)
==
- fvm::Sp(Ksl,U)
);
UEqn == -fvc::grad(p) + Ksl*Us;

\\ The pressure equations and energy equations are formed as in sonicFoam.
I wish to know the validity of using above method. The code I wrote was in similar way as that in sonicFoam and cfdemSolverPiso, and done necessary modifications. In current status the code is crashing after some iterations, which I am struggling to sort out. I would attach the code if you need.

Manoj