# Conjugated heat transfer problem:chtmultiregionSimpleFoam

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August 12, 2013, 00:54
Conjugated heat transfer problem:chtmultiregionSimpleFoam
#1
Member

ankur
Join Date: May 2012
Location: India
Posts: 50
Rep Power: 7
Dear all,

I am trying to solve a conjugated heat transfer problem. There are four rows of tubes with external circular fins on it. The tubes are given a constant temperature and then the conduction through the fins has to be considered. The outside fluid is air at a constant temperature and velocity. I am able to run the tutorial given in the openfoam but I am finding it to apply to my case. Another problem is I am making the geometry in Gmsh, can anybody help me how do I setup the case with the mesh from Gmsh. I am attaching a snapshot of my problem. Kindly have a look at it.
Attached Images
 conj.jpg (15.0 KB, 57 views)

 August 12, 2013, 04:51 #2 Senior Member   Elvis Join Date: Mar 2009 Location: Sindelfingen, Germany Posts: 602 Blog Entries: 5 Rep Power: 17 Hi, what about using Engrid (it is opensource software, free of charge) it creates OF meshes and the example is made for conjugate heat transfer with OPENFOAMŪ's chtMultiRegionSimpleFoam ? https://github.com/enGits/engrid/wik...heat-exchanger To create Geometries engrid prefers to get geomīs from blender and you should also should be able to import your gmesh stuff

 August 12, 2013, 05:20 #3 Member   ankur Join Date: May 2012 Location: India Posts: 50 Rep Power: 7 Hey Thanks for the quick reply. I am not familiar with Engrid but I have downloaded it and will try to understand how it works. I can create different volumes with gmsh also, for example fin is the solid part in my case and each fin is circular in shape with 6 faces. I have four fins, so is it like I have to make solid 1, solid 2, solid 3, solid 4 and then I have to make solid1_top, solid1_bottom etc..? Please guide me if u have any idea about this. I have single fluid region which is air, so one volume for that would be enough.

August 13, 2013, 03:37
#4
Member

MSarkar
Join Date: Dec 2009
Posts: 99
Rep Power: 10
Quote:
 Originally Posted by Ank Hey Thanks for the quick reply. I am not familiar with Engrid but I have downloaded it and will try to understand how it works. I can create different volumes with gmsh also, for example fin is the solid part in my case and each fin is circular in shape with 6 faces. I have four fins, so is it like I have to make solid 1, solid 2, solid 3, solid 4 and then I have to make solid1_top, solid1_bottom etc..? Please guide me if u have any idea about this. I have single fluid region which is air, so one volume for that would be enough.
Hi Ankur,

You can continue using gmsh if you want. It is not very difficult to convert the gmsh mesh to Foam mesh. You define all the surfaces and volumes properly in your geo file and create mesh. You use gmshToFoam utility to convert your mesh to foam format. If you have single mesh file for fluid and solid, you can use topoSet and subsetMesh to create appropriate regions. If conditions are same for all your solid regions, you can define one solid volume including all solids. A sample bash script is attached here. This shows the process for two regions.
Attached Files
 Meshconversion.tar.gz (615 Bytes, 22 views)

 August 13, 2013, 04:25 #5 Senior Member   Elvis Join Date: Mar 2009 Location: Sindelfingen, Germany Posts: 602 Blog Entries: 5 Rep Power: 17 Hi, Engrid has it own discussion here on CFD-Online http://www.cfd-online.com/Forums/engrid/ Engrid has itīs pros and cons, there is interesting development to come like "handling polyhedral cells directly inside engrid" or engrid is one of the few mesher supporting SU2 Oliver Gloth the "spiritus rector" of engrid is also here http://www.cfd-online.com/Forums/members/ogloth.html

 August 13, 2013, 05:14 #6 Member   ankur Join Date: May 2012 Location: India Posts: 50 Rep Power: 7 Hey Msarkar, Thanks alot for the help. I know how to use Gmsh and to run its mesh in openFoam, the only problem is the conjugate type problem in which how to divide the regions etc..but you have told me useful things and I am going to work upon it and will get back to you.

 August 13, 2013, 05:16 #7 Member   ankur Join Date: May 2012 Location: India Posts: 50 Rep Power: 7 Hey Elvis, I am going to see the Engrid also, It will take sometime to understand this new software, if I find it easier than Gmsh then will try to solve my problem by Engrid. As msarkar has replied that it is possible to make the mesh in Gmsh also so I am going to use Gmsh for now. Thanks for the help..I will see if its easy to learn Engrid.

 August 13, 2013, 13:42 #8 Member   ankur Join Date: May 2012 Location: India Posts: 50 Rep Power: 7 Hey Msarkar, Do we have to give the bounding box info ourselves? because topoSetDict.fluid1 is supposed to be already present..as I have understood.

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