[KarenRei]

I've been trying to figure out why my reaction's been blowing up... and it looks like I just found something that's probably Very Bad(tm). I wrote a program to sum up all of the species in each block, and they're sometimes amounting to significantly more than 1. Shortly after I start, the highest block sum is 1.57. In my last timestep before the crash, the the highest is over 5 - some blocks with individual species over 4. I mean, just crazy-high.

Googling the problem I see one person advise (over a decade ago):

It is also usefull to identify why you are observing this unphysical behavior. It could be a usefull exercise to check whether there is any coding problem. the known problems that results in this kind of behavior are usually:

1) unbounded numerical schemes;

2) diffusion fluxes that can not lead to \sum Yk = 1 (for example, if you are using unity Lewis number).

3) implicit segragated solver.

I wouldn't know how to go about fixing these, unfortunately... I'm only a novice with OpenFoam. My fvSchemes is:

fluxScheme Kurganov;

ddtSchemes
{
default Euler;
}

gradSchemes
{
default cellLimited Gauss linear 1; // Virðist vera meira stöðugt
}

divSchemes
{
default none;
div(phi,K) Gauss linearUpwind grad(U);
div(phid,p) Gauss limitedLinear 1;
div(phi,k) Gauss linearUpwind grad(U);
div(phi,epsilon) Gauss linearUpwind grad(U);
div(tauMC) Gauss linear;
div(phi,U) Gauss linearUpwind grad(U);
div(phi,Yi_h) Gauss upwind;
div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear limited corrected 0.33;
}

interpolationSchemes
{
default linear;
reconstruct(rho) vanLeer;
reconstruct(U) vanLeerV;
reconstruct(T) vanLeer;
}

snGradSchemes
{
default limited corrected 0.5;
}

and my fvSolution:

solvers
{
p
{
solver PBiCGStab;
preconditioner DILU;
tolerance 1e-14;
relTol 0.01;
}

pFinal
{
$p;
relTol 0.0;
}

"rho.*"
{
solver diagonal;
tolerance 1e-13;
relTol 0.0;
}

"(U|h|e|R|k|epsilon|omega)"
{
solver PBiCGStab;
preconditioner DILU;
tolerance 1e-13;
relTol 0.0;
}

"(U|h|e|R|k|epsilon|omega)Final"
{
$U;
relTol 0.0;
}

Yi
{
$hFinal;
}
}

PIMPLE
{
momentumPredictor no;
nOuterCorrectors 1;
nCorrectors 2;
nNonOrthogonalCorrectors 0;
transonic yes;
}

My thermoType is:

thermoType
{
type hePsiThermo;
mixture reactingMixture;
transport sutherland;
thermo janaf;
equationOfState perfectGas;
specie specie;
energy sensibleEnthalpy;
}

... and all of my reactions have transport As = 1.67212e-6, Ts = 170.672.

chemistry is EulerImplicit, cTauChem 1.0, equilibriumRateLimiter off.

Any clue what could be wrong or what I could try?

[flyingmercury]

Hi, I am just wondering if you have found out the reason and solved this issue eventually?

Thanks.

[KarenRei]

My experience has generally been that such problems, at least with reactingFoam, is that they're triggered by having one of your reactions improperly balanced. I think another cause can be if your species percents don't addup to 1. I may have encountered some other things that can generate this problem but I don't recall them.

[ravicfdd]

I know this is very late but maybe this will be useful to someone else who has the same problem. Often times when I get this error it is due to improper initialization in the 0 folder. If say you have initialized at the inlet that O2 is entering with a mass fraction of 0.232, then you should make sure the addition of all other species at the inlet + O2 at the inlet sum to 1. Ensure this for every patch and the internalField in your 0 folder. If this is not done, the solver will give nonphysical results.