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-   -   Power Law Velocity (http://www.cfd-online.com/Forums/openfoam-pre-processing/114376-power-law-velocity.html)

sihaqqi March 10, 2013 02:42

Power Law Velocity
 
Hi everyone

I am a beginner in openFoam. I have a geometry where two pipes are connected at 90degree. Flow is turbulent. I have made my geometry but now I want to have one seventh power law velocity profile set up in my boundary conditions. I have attached my files if anyone experienced can spare a few moments. Pipe diameter is 72.54mm. Mach number is 0.22 and medium is air. Fow enters vertically upwards in +Y and then turn in the bend at +X. Patches are inlet, outlet, upstream, downstream, symmetry.

Following is input of my "epsilon" file

dimensions [ 0 2 -3 0 0 0 0 ];

internalField uniform 1;

boundaryField
{
inlet
{
type powerLawVelocity;
n (7 0 0);
y (0 0.7254 0);
maxValue 10;
value uniform (0 0 0);
}

outlet
{
type inletOutlet;
inletValue $internalField;
}

walls
{
type epsilonWallFunction;
value uniform 0;
}

symmetry
{
type inletOutlet;
}
}


Input for P

internalField uniform 0;

boundaryField
{
inlet
{
type powerLawVelocity;
n (7 0 0);
y (0 0.7254 0);
maxValue 10;
value uniform (0 0 0);
}

outlet
{
type fixedValue;
value uniform 0;
}

upstream
{
type wall;
}

downstream
{
type wall;
}

symmetry
{
type zeroGradient;
}

}

michielm March 10, 2013 03:42

could you specify what you want us to answer/what the problem is you are experiencing?

sihaqqi March 10, 2013 09:56

Dear Michiel

Many thanks for your response. My problem is I want some piping tutorials with power law boundary conditions and the reason behind them. This is what mu Masters by research thesis is about. I want to know how to set up 1/7th power law velocity profile in all k, p, epsilon, u and Nut and NuTilda files so that my system works well. Patches are inlet, outlet, symmetry, upstream, downstream. Do you have any tutorial with some explanation on this type of problem with correct values of n and y. With my values, simpleFoam is giving errors which I do not understand at all.

Regards

michielm March 10, 2013 10:53

I can't find a tutorial in the OpenFOAM tutorials folder (i tried: grep -r -i "powerlawvelocity" *), but you can find an example at the chalmers PhD course on CFD in OF:
Tutorial Power law velocity inlet, InterFoam

EDIT: just an addition, I noticed that the report of the chalmers course uses 1.5-dev so I guess the powerLawVelocity BC is also only available in the -dev versions of OpenFOAM.


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