CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM

viewfactor

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   August 15, 2011, 13:10
Default viewfactor
  #1
New Member
 
javad
Join Date: Aug 2010
Posts: 22
Rep Power: 7
javad814 is on a distinguished road
thanks for your attention
I can't understand the file named viewFactorDict.
I want to know that what the below parameters mean.
writeViewFactorMatrix true;
writeFacesAgglomeration true;
writePatchViewFactors false;
nFacesInCoarsestLevel 24;
featureAngle 10;
thease are from the tutorials ,sample multiRegionHeaterRadiation.
below is the hole file:

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.0.0 |
| \\ / A nd | Web: www.OpenFOAM.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object viewFactorsDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //


writeViewFactorMatrix true;
writeFacesAgglomeration true;
writePatchViewFactors false;

topAir_to_heater
{
nFacesInCoarsestLevel 24;
featureAngle 10;
}

topAir_to_leftSolid
{
nFacesInCoarsestLevel 20;
featureAngle 10;
}

topAir_to_rightSolid
{
nFacesInCoarsestLevel 20;
featureAngle 10;
}

minX
{
nFacesInCoarsestLevel 10;
featureAngle 10;
}

maxY
{
nFacesInCoarsestLevel 40;
featureAngle 10;
}

minZ
{
nFacesInCoarsestLevel 20;
featureAngle 10;
}

maxX
{
nFacesInCoarsestLevel 10;
featureAngle 10;
}

maxZ
{
nFacesInCoarsestLevel 20;
featureAngle 10;
}


// ************************************************** *********************** //
javad814 is offline   Reply With Quote

Old   August 15, 2011, 14:48
Default
  #2
Senior Member
 
Mirko Vukovic
Join Date: Mar 2009
Posts: 159
Rep Power: 9
mirko is on a distinguished road
Quote:
Originally Posted by javad814 View Post
thanks for your attention
I can't understand the file named viewFactorDict.
I want to know that what the below parameters mean.
writeViewFactorMatrix true;
writeFacesAgglomeration true;
writePatchViewFactors false;
nFacesInCoarsestLevel 24;
featureAngle 10;
thease are from the tutorials ,sample multiRegionHeaterRadiation.
below is the hole file:

... stuff deleted
Unfortunately you will have to hit the books, as at least some of the stuff has to do with the numerical method.

As I recall from Fluent, faceAgglomeration has to do with merging multiple face elements. So for example if the body has a surface mesh with 10,000 elements, when you agglomerate them, you may end up with a 1000 elements. This reduces the size of the ViewFactor matrix.

Other than the need to reduce the computational load, agglomeration may have to do with the fact that radiation and conduction/convection are very different problems, and that the mesh necessary for one may be too fine for the other. But I am only guessing.

I need to dig through the code more to understand better where agglomeration is happening (looks like somewhere in faceAgglomerate.C)

Mirko
mirko is offline   Reply With Quote

Old   August 18, 2011, 05:24
Default thanks for your post
  #3
New Member
 
javad
Join Date: Aug 2010
Posts: 22
Rep Power: 7
javad814 is on a distinguished road
below is more information:
path(openFoam 2.0.0): tutorial/heatTransfer/chtMultiRegionSimpleFoam/multiRegionHeaterRadiation/constant/bottomAir/viewFactorsDict
in this sample a new radiation model is used and i must understand how it works and which files are necessary for this model.
to see the results in paraview you must type each region seperatly for example:
paraFoam -region heater
then you can see other regions in paraview as follows:
File>Open
now you can select any region you want,like
multiRegionHeaterRadiation{bottomAir}.OpenFOAM
javad814 is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Request for help on viewfactor calculation raghav FLUENT 1 November 17, 2008 00:14
Radiation and miscellaneous enhancements vtk_fan OpenFOAM Running, Solving & CFD 6 February 18, 2008 00:49
writing viewfactor file Jonas FLUENT 0 September 1, 2006 06:58


All times are GMT -4. The time now is 00:10.