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programming of GGI RPM

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Old   September 24, 2012, 05:18
Default programming of GGI RPM
  #1
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Andreas Wendy
Join Date: Aug 2012
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Hi Folks,

i am trying to create a simulation with autorotation with the uses OF 1.6 extend and the GGI. Now i was trying to do some small changes in the rotation speed of my mesh but it will not work.
for the beginning i tried do amke the speed time dependent by using the equation:
rpm 10*sin(pi*time);

but there was no effect. it was allways the rpm of 10 used. so i used some more easy expression:

dynamicMeshDict:
Quote:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 1.3 |
| \\ / A nd | Web: http://www.openfoam.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/

FoamFile
{
version 2.0;
format ascii;
class dictionary;
object dynamicMeshDict;
}

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

dynamicFvMeshLib "libtopoChangerFvMesh.so";
dynamicFvMesh mixerGgiFvMesh;
roundperminute 10 + 10;

mixerGgiFvMeshCoeffs
{
coordinateSystem
{
type cylindrical;
origin (0 0 0);
axis (0 0 1);
direction (1 0 0);
}

rpm $roundperminute;

slider
{
moving (insideSlider);
static (outsideSlider);
}
}

// ************************************************** *********************** //
Result:
Quote:
.
.
.
Create time

Create dynamic mesh for time = 0

Selecting dynamicFvMesh mixerGgiFvMesh
Initializing the GGI interpolator between master/shadow patches: outsideSlider/insideSlider
Time = 0
Adding zones and modifiers to the mesh
Copying existing face zones
Number of cells in the moving region: 5000
Adding point, face and cell zones
Mixer mesh:
origin: (0 0 0)
axis : (0 0 1)
rpm : 10
.
.
.
also i tried:
dynamicMeshDict:
Quote:
dynamicFvMeshLib "libtopoChangerFvMesh.so";
dynamicFvMesh mixerGgiFvMesh;
roundperminute 10+10;

mixerGgiFvMeshCoeffs
{
coordinateSystem
{
type cylindrical;
origin (0 0 0);
axis (0 0 1);
direction (1 0 0);
}

rpm $roundperminute;

slider
{
moving (insideSlider);
static (outsideSlider);
}
}
but the result was always a rotational speed of 10 rpm. how can i "force" OpenFoam to do the calculations an not only to include the first number of the equation?

best wishes

Andy
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Old   September 25, 2012, 00:16
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Philippose Rajan
Join Date: Mar 2009
Location: Germany
Posts: 530
Rep Power: 16
philippose will become famous soon enough
Hi there,

A Good day to you!

If I remember right, and if things are still the same as they were (which I am quite positive is the case), you cannot use expressions in your OpenFOAM dictionary files.

For example, "10 + 10" does not work, because when OpenFOAM processes the dictionary files, it needs to recognise the fact that "10 + 10" actually is a mathematical expression, and then "solve" or "evaluate" the expression.... This functionality is not directly available within OpenFOAM.

This could be the reason why you are always getting "10" as the RPM.

Wishing you a great day ahead!


Philippose
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