New Post/Thread: OpenFOAM - Problem running perturbUCyl

CFD Online OpenFOAM Forums openfoam at cfd-online.com
Fri Mar 23 03:12:14 MDT 2012


Hello,

dhruv has just posted in the OpenFOAM forum of CFD Online Discussion Forums under the title of Problem running perturbUCyl.

This thread is located at http://www.cfd-online.com/Forums/openfoam/98337-problem-running-perturbucyl.html

Here is the message that has just been posted:
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Hi Sen, 

Sorry for the late reply. Can you tell me the following:

1. What is the velocity that you impose at the beginning of the channel?
2. How did you calculate the expected U_tau and Re_tau?

I am also having the problems with perturbU, that it does not generate the fields in my whole geometry. I am pretty sure, that I am not wrong in giving the dimensions for the channel case, that I have. I am attaching the pictures of the fields getting generated. As you can see, Uz is being generated only in a part of the channel, and the whole thing. 

My transport properties are 

Code:
---------
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.1.x                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "constant";
    object      transportProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

Ubar            Ubar [ 0 1 -1 0 0 0 0 ] ( 0.8 0 0 );

Retau           Retau [ 0 0 0 0 0 0 0 ] 5;

transportModel  Newtonian;

nu              nu [ 0 2 -1 0 0 0 0 ] 1.52e-06;

//Retau           Retau [ 0 0 0 0 0 0 0 ] 500;

CrossPowerLawCoeffs
{
    nu0             nu0 [ 0 2 -1 0 0 0 0 ] 1e-06;
    nuInf           nuInf [ 0 2 -1 0 0 0 0 ] 1e-06;
    m               m [ 0 0 1 0 0 0 0 ] 1;
    n               n [ 0 0 0 0 0 0 0 ] 1;
}

BirdCarreauCoeffs
{
    nu0             nu0 [ 0 2 -1 0 0 0 0 ] 1e-06;
    nuInf           nuInf [ 0 2 -1 0 0 0 0 ] 1e-06;
    k               k [ 0 0 1 0 0 0 0 ] 0;
    n               n [ 0 0 0 0 0 0 0 ] 1;
}


// ************************************************************************* //
---------
My perturbUDict file is 


Code:
---------
/*---------------------------------------------------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  1.0                                   |
|   \\  /    A nd           | Web:      http://www.openfoam.org               |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/

FoamFile
{
    version         2.0;
    format          ascii;

    root            "/home/penfold/mattijs/foam/mattijs2.1/run/icoFoam";
    case            "cavity";
    instance        "system";
    local           "";

    class           dictionary;
    object          perturbUDict;
}

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


// Expected turbulent Re(tau) Reynolds number with respect to utau
Retau 395;

// Streamwise component of flow. 0=x, 1=y, 2=z
streamwise 0;

// Spanwise component of flow. 0=x, 1=y, 2=z
spanwise 2;

// Halfheight of channel. This is the direction normal to both streamwise and
// spanwise directions.
h 0.0024;

// Set (overwrite) velocity to laminar profile
setBulk false;

// Perturb velocity with some cosine like perturbations
perturb true;

// Perturbation properties
//wall normal circulation as a fraction of Ubar/utau
duplus 0.25;
//spanwise perturbation spacing in wall units
betaPlus 200;
//streamwise perturbation spacing in wall units
alphaPlus 500;
//transverse decay
sigma 0.00055;
//linear perturbation amplitude as a fraction of Ubar
epsilon 0.005;


// ************************************************************************* //
---------

---Quote (Originally by sen.1986)---
Hello Dhruv, 

I got rid of the previous problem. I redid my meshing and modeling, this time using blockmeshdict. The reported problems are mainly caused due to orientation problem of faces. 

Anyway, my problem with perturbU is far from being over. The 'U' field that perturbU generates, is very unreasonable. The Ux are in the range of ~4000, Uy is 0 (understandably so), Uz is also 0 (Why?).

Do you have any idea, what might be causing this? Also, it would be helpful if you could attach three files, your 'transportproperties', 'U' after you run perturbU and the script, perturbU.c. Sorry for sounding too demanding.
---End Quote---

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