CFD Online Discussion Forums - Boussinesq Approximation in OpenFOAM 7

Hi all,

I have been using buoyantBoussinesqPimpleFoam for some time now quite happily in OpenFoam 6 and earlier. However, I would like to be able to convert to version 7, where the boussinesq solver has been integrated into the general buoyantPimpleFoam solver (I think it should be easier to simulate a heat sink of specific power in this solver).

Unfortunately, I have not been able to run a model that even comes close to working other than the hotRoomBoussinesq tutorial.

Has anybody else had more success?

The model of mine that I am trying to run wildly diverges, especially in T results, despite there being no heat source or sink, just a momentum source to simulate a pump.

Originally, it would do one or two time steps then in the next exceed the number of permitted iterations and spit out an error like

Code:

--> FOAM FATAL ERROR:

Negative initial temperature T0: -[large number]

At the moment I have temperature limits to keep it within the 900-1500K range, but cells in the mesh just seem to choose one or the other of those two values:

Code:

#0  Foam::error::printStack(Foam::Ostream&) at ??:?

#1  Foam::sigFpe::sigHandler(int) at ??:?

#2  ? in "/lib64/libc.so.6"

#3  Foam::DILUPreconditioner::calcReciprocalD(Foam::Field<double>&, Foam::lduMatrix const&) at ??:?

#4  Foam::DILUPreconditioner::DILUPreconditioner(Foam::lduMatrix::solver const&, Foam::dictionary const&) at ??:?

#5  Foam::lduMatrix::preconditioner::addasymMatrixConstructorToTable<Foam::DILUPreconditioner>::New(Foam::lduMatrix::solver const&, Foam::dictionary const&) at ??:?

#6  Foam::lduMatrix::preconditioner::New(Foam::lduMatrix::solver const&, Foam::dictionary const&) at ??:?

#7  Foam::PBiCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:?

#8  ? at ??:?

#9  ? at ??:?

#10  ? at ??:?

#11  ? at ??:?

#12  __libc_start_main in "/lib64/libc.so.6"

#13  ? at ??:?

/opt/site/sge/default/spool/node405/job_scripts/1039376: line 9: 80501 Floating point exceptionbuoyantPimpleFoam

It seems to struggle most with the U solvers. U values are similarly divergent, ranging form 0m/s to ridiculous numbers.

I would be very grateful for any help from someone who has had success with Boussinesq calculations in OpenFOAM 7.

Thank you,

Alex