[gentodin]

Hi all,

I am trying to replicate the simulation from ANSYS fluent to OpenFOAM but I could not find some settings or do not know how to set them in OF.(This is my way of learning, feel free to drop comment for a better way).

The following are the areas I am looking at fvSolution and fvScheme in the OF settings.

Currently there are 4 segments of input parameters I divided them into and each contains question as shown below:

1) The fvSolution algorithm used was PISO

Fluent settings:
Skewness Correction 1
Neighbor Correction 1

OF settings:
PIMPLE
{
nNonOrthogonalCorrectors 1
nCorrectors 1
nOuterCorrectors 1
}


Questions:
When the simulation is running in fluent, there is an additional option of setting max iteration per timestep, does this iteration refer to total no. of PISO loop per timestep or the control of other loops?



2) fvSchemes grad and div settings

fluent settings:
gradient, leastsquareCellBased
Pressure, Second Order upwind
Momentum, Second Order upwind
TKE, Second Order upwind
TDR, Second Order upwind
Energy, Second Order upwind
Transient Formulation, First Order implicit

OF settings:
ddtSchemes
{
default Euler;
}

gradSchemes
{
default none;

grad(U) leastSquares;
grad(T) leastSquares;
grad(k) leastSquares;
grad(epsilon) leastSquares;
grad(R) leastSquares;

}

divSchemes
{
default none;

div(phi,U) Gauss linearUpwind grad(U);
div(phi,T) Gauss linearUpwind grad(T);
div(phi,k) Gauss linearUpwind grad(k);
div(phi,epsilon) Gauss linearUpwind grad(epsilon);
div(phi,R) Gauss linearUpwind grad(R);
div(R) Gauss linearUpwind grad(R);
div((nuEff*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear uncorrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default uncorrected;
}

Questions:

Are the laplacianSchemes/interpolationschemes in fluent follow the individual schemes that are present? i.e. momentum follows all second order upwind for div, laplacian and interpolation schemes.

Why can't set linearUpwind for div((nuEff*dev2(T(grad(U))))) under divSchemes?


3) fvSolution Residuals

All settings are the same except for continuity and pressure.

Does anyone know where to set the Pressure residuals in fluent?
Does anyone know where to set the continuity Residuals in OF?


4) fvSolution Under-Relaxation Factors

Fluent settings:
Pressure 0.3
Density 1
Body Forces 1
Momentum 0.7
TKE 0.8
TDR 0.8
Turbulent Viscosity 1
Energy 1

OF settings:
Momentum 0.7
TKE 0.8
TDR 0.8

Question: How do I set Pressure, Density, Body Forces and Turbulent Viscosity Under relaxation factors in OF. ?

THANK YOU to anyone that can answer any of these questions.

[jayson]

Originally Posted by gentodin

Hi all,

I am trying to replicate the simulation from ANSYS fluent to OpenFOAM but I could not find some settings or do not know how to set them in OF.(This is my way of learning, feel free to drop comment for a better way).

The following are the areas I am looking at fvSolution and fvScheme in the OF settings.

Currently there are 4 segments of input parameters I divided them into and each contains question as shown below:

1) The fvSolution algorithm used was PISO

Fluent settings:
Skewness Correction 1
Neighbor Correction 1

OF settings:
PIMPLE
{
nNonOrthogonalCorrectors 1
nCorrectors 1
nOuterCorrectors 1
}


Questions:
When the simulation is running in fluent, there is an additional option of setting max iteration per timestep, does this iteration refer to total no. of PISO loop per timestep or the control of other loops?



2) fvSchemes grad and div settings

fluent settings:
gradient, leastsquareCellBased
Pressure, Second Order upwind
Momentum, Second Order upwind
TKE, Second Order upwind
TDR, Second Order upwind
Energy, Second Order upwind
Transient Formulation, First Order implicit

OF settings:
ddtSchemes
{
default Euler;
}

gradSchemes
{
default none;

grad(U) leastSquares;
grad(T) leastSquares;
grad(k) leastSquares;
grad(epsilon) leastSquares;
grad(R) leastSquares;

}

divSchemes
{
default none;

div(phi,U) Gauss linearUpwind grad(U);
div(phi,T) Gauss linearUpwind grad(T);
div(phi,k) Gauss linearUpwind grad(k);
div(phi,epsilon) Gauss linearUpwind grad(epsilon);
div(phi,R) Gauss linearUpwind grad(R);
div(R) Gauss linearUpwind grad(R);
div((nuEff*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default Gauss linear uncorrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default uncorrected;
}

Questions:

Are the laplacianSchemes/interpolationschemes in fluent follow the individual schemes that are present? i.e. momentum follows all second order upwind for div, laplacian and interpolation schemes.

Why can't set linearUpwind for div((nuEff*dev2(T(grad(U))))) under divSchemes?


3) fvSolution Residuals

All settings are the same except for continuity and pressure.

Does anyone know where to set the Pressure residuals in fluent?
Does anyone know where to set the continuity Residuals in OF?


4) fvSolution Under-Relaxation Factors

Fluent settings:
Pressure 0.3
Density 1
Body Forces 1
Momentum 0.7
TKE 0.8
TDR 0.8
Turbulent Viscosity 1
Energy 1

OF settings:
Momentum 0.7
TKE 0.8
TDR 0.8

Question: How do I set Pressure, Density, Body Forces and Turbulent Viscosity Under relaxation factors in OF. ?

THANK YOU to anyone that can answer any of these questions.

Did you solve this problem??

[gentodin]

Originally Posted by jayson

Did you solve this problem??

I manage to find out about the 1st question where the max iteration in ANSYS fluent is referring to max outer iterations per timestep as shown here:

For 4th question, setting pressure relaxation is simple typing this in fvSolution file in OF:

relaxationFactors
{
equations
{

p 0.3; //Pressure relaxation
pFinal 1;

U 0.7; //Velocity relaxation
UFinal 1;

}
}