Dear all, I am using OpenFoam 5.0 and working on heat transfer simulation using chtMultiRegionSimpleFoam solver.
1. I have a temperature data file which equals to the face center length of a surface region. This temp file has "0" temp in some faces and rest with variable temperature. (say out of 1000 temp values, 400 are 0s and rest are varying). This is a Dirichet BC.
2. I have used this temperature data and simulated it.
But now, I need this "zero" temperature value to be changed to convection BC. I know the parameters for convection BC. The convection parameters are as given below.
type externalWallHeatFluxTemperature;
mode coefficient;
Ta constant 22;
h uniform 10;
kappaMethod solidThermo;
value uniform 30;
But, how do I change the zero temperature cells to different boundary condition? Or, how can I create a Patch based on this temp=0 faceCentre cells? 3. I checked with SetFields (FieldToCell), but I can only give scalar value there and not BC.
I have attached two images of the images, one from top and isolated view. The blue color shows the 0 temperature where BC need to be changed.
I hope the question is well understood. Any leads will be appreciated.
Regards,
Sunag R A.
Hi Sunag,
If I understand correctly, you wish to apply two different kinds of boundaries on a single boundary based on the condition of a known temperature field.
This is unfortunately not that straight forward to apply.
A few options are available.
1.) mixed boundary conditions would allow you to specify Robin boundaries. Where you can apply either a Dirchlet, Neumann or Robin based on the choice of the reference value. These are however constant, so it would not be possible to apply a temperature based heat flux boundary by specifying a convective heat flux coefficient as with externalWallHeatFluxTemperature boundary condition.
2.) The second option, and probably your best bet would be to try a codedMixed type boundary condition (I can't recall if OF 5.0 already had this). With a codedMixed boundary you have to get your hands dirty with some coding but you will definitely be able to formulate a boundary that you want.
3.) The third option I can think of is to try groovyBC (from swak4Foam). GroovyBC allows you to define a mixed boundary condition, but the inline equations can include if statements, so you would be able to apply your conditional switch.
Best of luck,
Alfred
Hi Sunag,
If I understand clearly, you want to define two different boundary conditons on one single patch. So, is it possible for you to split the current patch into two different patches, where you can easily define their own boundary condition? We usually put the regions with same boundary conditions into one patch.
Best,
Changchang
Hi Changchang Wang,
Yes. It is possible to split the current patch into two different patches. Since I am working in OpenFoam, I will have access to mesh details so that I can get the face values of Field and then create a patch from it.
You can check the discussion in the link provided below (This is a 2 page discussion):
https://www.cfd-online.com/Forums/openfoam-solving/235273-how-change-set-different-boundary-condition-particular-cell-region.html
Well, I am facing few errors with respect to this. I am still working on it.
Regards,
Sunag R A.
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