HELP!!! (ReactingFoam)
 

Hi to all,

it would be really really really great if someone had an idea why this case isn't working: I'm simulating a micromixer with two inlets and one outlet, whereby the mixing task contains a reaction. I attached all the files I'm using for this case. blockMesh works, but I get the following error using reactingFoam and I'm currently running out of ideas how to solve it...

Create time
Create mesh for time = 0
// using new solver syntax:
rho
{
solver PCG;
preconditioner DIC;
tolerance 1e-06;
relTol 0;
}
// using new solver syntax:
U
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-06;
relTol 0;
}
// using new solver syntax:
p
{
solver PCG;
preconditioner DIC;
tolerance 1e-09;
relTol 0;
}
// using new solver syntax:
Yi
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-06;
relTol 0;
}
// using new solver syntax:
h
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-06;
relTol 0;
}
// using new solver syntax:
k
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-06;
relTol 0;
}
// using new solver syntax:
epsilon
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-06;
relTol 0;
}
Reading chemistry properties
Reading g
Reading thermophysicalProperties
Selecting psiChemistryModel ODEChemistryModel<gasThermoPhysics>
Selecting thermodynamics package hPsiMixtureThermo<reactingMixture<gasThermoPhysics >>
Selecting chemistryReader chemkinReader
Selecting chemistrySolver ode
Selecting ODE solver SIBS
ODEChemistryModel: Number of species = 5 and reactions = 1
Reading field U
Reading/calculating face flux field phi
Creating turbulence model.
Selecting turbulence model type laminar
Creating field DpDt
Courant Number mean: 10.0785 max: 160
Starting time loop
Courant Number mean: 0.00629904 max: 0.0999994
deltaT = 6.24996e-07
Time = 6.24996e-07
Solving chemistry
#0 Foam::error::printStack(Foam::Ostream&) in "/home/steffi/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/home/steffi/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libOpenFOAM.so"
#2 Uninterpreted:
#3 Foam::divide(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) in "/home/steffi/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libOpenFOAM.so"
#4 void Foam::divide<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/home/steffi/OpenFOAM/OpenFOAM-1.6/applications/bin/linuxGccDPOpt/reactingFoam"
#5 Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam::operator/<Foam::fvPatchField, Foam::volMesh>(Foam::tmp<Foam::GeometricField<doub le, Foam::fvPatchField, Foam::volMesh> > const&, Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > const&) in "/home/steffi/OpenFOAM/OpenFOAM-1.6/applications/bin/linuxGccDPOpt/reactingFoam"
#6 main in "/home/steffi/OpenFOAM/OpenFOAM-1.6/applications/bin/linuxGccDPOpt/reactingFoam"
#7 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6"
#8 _start at /usr/src/packages/BUILD/glibc-2.9/csu/../sysdeps/i386/elf/start.S:122
Floating point exception

Please check that you use the right chem.inp file. The output says that you use a mechanism with 5 species and one reaction, but the one you want is probably 7 species and 2 reactions... check your constant/thermophysicalProperties file. Also, use a proper inertSpecie (the species that is not solved for and which make sure that mass fractions in each cell always sum up to one)... maybe H2O would work, but not N2 since it is not a part of your system.


Further, make sure that your initial conditions and boundary conditions for species is well defined, i.e. the mass fractions should all sum up to one. For instance you have both Y_H+ and Y_H2O equal to 1 for internalField.

Good luck!

Thanks so much for your ideas, I changed some of the import data and now the simulation basically seems to work in macroscopic dimensions.

Sorry in advance for this maybe stupid question, but I intend to model reactions in a micromixer, and for the simulations I've done with twoLiquidMixingFoam I used to set up a transportProperties-file, where viscosities and the diffusion coefficient are defined (as diffusion is the main mixing driving force in microscopic dimensions).
I aim to model reactions beween two streams of water with only small concentrations of solute ions (Villermaux-Dushman-reaction). In this case I would need to account for the diffusion between both water-based inlet streams.

I would appreciate any help or suggestions :)

Glad it helped you!


Regarding mixing and reaction in liquid substances, I can't help you that much I am afraid. I would guess that you are on a good trail anyway. Probably you will need to write your own solver, which should not be too hard.... look at the reactingFoam and twoLiquidMixingFoam solvers to get an idea. If your mixture is releasing significant heat you probably need to deal with that too... the problem may then be a bit similar to buoyancy problems in liquid.

I guess someone else here can provide more accurate ideas.

Kalle