[sivakumar]

Hi All,
I am looking for a small information and help, I have done many simulation with MRFSimpleFoam.

now I am facing small issue for the pressure boundary condition.
I was using 0/p:

inlet zeroGradient;

outlet fixedValue;
value 0;

I plotted the pressure curve close to the surface (see fig)

computational domain is -1.5 m inlet and 6 m of outlet (from the fan)
the attached pressure curve looks fine upto 5.5m but after that its started decreasing due to the given outlet boundary condition.

I am expecting the curve to be reasonable straight line, is there any other outlet BC's to produce such curve?

please help me with some sort of information.

Thanks,
Sivakumar

[ngj]

Good evening Sivakumar

Could you also please post your velocity boundary conditions and your fvSchemes file?
I have seen something similar in the past and that was related to the choice of time integration scheme, but I cannot find the thread. The conclusion was that it helped to using Euler.

Kind regards

Niels

[sivakumar]

Hi Niels, Good evening thanks for your quick reply,
0/U

inlet flowRateInletVelocity;

outlet zeroGradient;

and the fvSchemes are as follows

ddtSchemes
{
default steadyState;
}

gradSchemes
{
default Gauss linear;
grad(p) leastSquares;
grad(omega) Gauss linear;
grad(epsilon) Gauss linear;
grad(U) Gauss linear;
grad(k) Gauss linear;
}

divSchemes
{
default none;
div(phi,U) Gauss linearUpwindV grad(U);
div(phi,k) Gauss upwind;
div(phi,omega) Gauss upwind;
div(phi,epsilon) Gauss upwind ;
div((nuEff*dev(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
default none;
laplacian(nuEff,U) Gauss linear limited 0.7;
laplacian((1|A(U)),p) Gauss linear limited 1;
laplacian(DkEff,k) Gauss linear limited 0.7;
laplacian(DepsilonEff,epsilon) Gauss linear limited 0.5;
}

interpolationSchemes
{
default linear;
interpolate(U) linear;
}

snGradSchemes
{
default limited 0.5;
}

fluxRequired
{
default no;
p ;
}


Thanks,
Sivakumar

[ngj]

Hi

I am sorry, but nothing come to my mind.

Good luck,

Niels

[sivakumar]

Hi Niels,
Its fine thanks for your time, if you dont mind can you please give me the thread link.


Thanks,
Sivakumar

[sivakumar]

hi there,
I am sorry, Euler time integration method is not solving the problem.

Thanks,
Sivakumar