[saip]

Hi People,


Problem statement:- Is to simulate the propagation of a free gaseous jet with 2 inlets One for gas and another for air.
Geometry:- A Pipe ( gas inlet ) with a length 200mm and Diameter 26mm and is opening into a chamber ( Air inlet ) of length 1000mm and diameter 285mm.
Initial Conditions:- Gas velocity 32 m/s; Air velocity 12 m/s; Temp 300 K; Pressure 1 bar.


I tried to simulate using rhoPimpleFoam as I am experiencing the negative initial temp error. I request people for suggestions to overcome this error. Please find the attachment. If anybody needs case setup I can share here.


Thank you.

[arvindpj]

Could you share your thermoTypes? Have you used fvOptions to limit Temperature?

 

limitT
{
	type            limitTemperature;
	//region fluid;
	active          yes;
	limitTemperatureCoeffs
	{
		selectionMode   all;
		min             250;
		max             1000;
	}
}

[saip]

Hi Jay,

Thank you for replying. Here it is fvSchemes, and fvSolutions.

fvSchemes:-

/*--------------------------------*- C++ -*----------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Version: 6
\\/ M anipulation |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
default backward;
}

gradSchemes
{
default Gauss linear;
}

divSchemes
{
default none;
div(phi,U) Gauss LUST grad(U);
div(phi,e) Gauss LUST grad(e);
div(phi,K) Gauss linear;
div(phiv,p) Gauss linear;
div(phi,k) Gauss limitedLinear 1;
div(phi,B) Gauss limitedLinear 1;
div(phi,muTilda) Gauss limitedLinear 1;
div(B) Gauss linear;
div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear corrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default corrected;
}


// ************************************************** *********************** //


fvSolutions


/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 5 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
"(p|rho)"
{
solver PCG;
preconditioner DIC;
tolerance 1e-6;
relTol 0.01;
}

"(p|rho)Final"
{
$p;
relTol 0;
}

"(U|e|k|nuTilda)"
{
solver smoothSolver;
smoother symGaussSeidel;
tolerance 1e-6;
relTol 0.01;
}

"(U|e|k|nuTilda)Final"
{
$U;
relTol 0;
}
}

PIMPLE
{
momentumPredictor yes;
nOuterCorrectors 3;
nCorrectors 1;
nNonOrthogonalCorrectors 0;

pMinFactor 0.5;
pMaxFactor 2.0;
}

relaxationFactors
{
equations
{
".*" 1;
}
}

// ************************************************** *********************** //

[pete20r2]

Before you try changing other setup variables, do what Arvind suggested and put that code in a fvOptions file. I have used it to start every thermo job I've done for the last few years.
When the simulation is done, check there are no cells at 250 or 1000 to make sure the limiter is not influencing your real results or something else isn't wrong.