[zfaraday]

Dear FOAMers,

As I commented in my latest thread (extrange-behaviour-when-solving-circuitboardcooling-tutorial) opened recently, lately I have been testing the Circuit Board Cooling tutorial. My main aim was to discover the procedure of creating 3D baffles for thermal applications in a multi region problem.

I had a bunch of problems during my several attempts, because the tutorial is made up of only one region and I didn't know the exact execution order of the multiple applications needed in order to create the geometry I need. The utilities I used in my case are:

• I generated the base geometry with blockMesh,
• created the multiple cellZones using topoSet utility,
• created the baffles with createBaffles, of course (the faceZone needed for it I generated it either with a stl file or with topoSet, I tried both cases)
• separated the multiple regions with splitMeshRegions utility

However I got confused because I didn't know if I had to create the baffle first and then split the regions or the opposite (I tried both, I tried almost everything). These are the Allrun scripts that I think should suit my needs:

1. Baffle creation done at the end (not sure about the -region flag use)
   

   blockMesh
   cp -rf 0.org 0     //like is done in the tutorial (same files used)
   topoSet
   splitMeshRegions -cellZones -overwrite
   createBaffles -region air -overwrite

2. Baffles are created before regions are created
   

   blockMesh
   cp -rf 0.org 0     //like is done in the tutorial (same files used)
   topoSet
   createBaffles -overwrite
   splitMeshRegions -cellZones -overwrite

________________________________1st Question________________________________

· What is the most proper procedure to generate correctly the regions and the baffle? Did I miss any step? How would you do that?

__________________________________________________ ________________________



I'll let you know that both procedures created the baffle patches but no one generated the 3D baffle region it is supposed to be generated after the process is finished. That is, something didn't work well. As this was my first attempt creating 3D thermal baffles I finally decided to simplify my case, because I thought that maybe the problem came from the multi region specification. Thus, I ended up creating a single air block with a baffle (very, very similar to the tutorial case, but all was made by me except the baffle definition that was taken from the tutorial).

My surprise was that the result was the same I got before with the multi region case (it was the same geometry but without using the topoSet step in the Allrun script). Baffle patches were created but no 3D baffle region nowhere...

At this point, I tried to find out what was happening and I found out something suspicious in the log.createBaffles and the 0/T files. Attached you can see both files coming from the tutorial (*.txt) and from my personal attempt (*.myCase.txt). The main difference between both log files is that this piece is missing in my case but not in the tutorial case:

Selecting extrudeModel linearNormal
    Selecting region model functions
    none

The thermal baffle is 3D 

Selecting thermodynamics package 
{
    type            heSolidThermo;
    mixture         pureMixture;
    transport       constIso;
    thermo          hConst;
    equationOfState rhoConst;
    specie          specie;
    energy          sensibleEnthalpy;
}

Selecting radiationModel opaqueSolid
Selecting absorptionEmissionModel none
Selecting scatterModel none

I guess this is the point where the region is created so, if I don't see it in my log file it means the baffle region is not created, is it?

________________________________2nd Question________________________________

· Why is the region not created if I used exactly the same specification in the createBaffleDict file that is used in the tutorial? What am I doing wrong? I'm begining to get crazy for it since I have tried it a bunch of times and it never works in my case but keeps working in the tutorial case...

__________________________________________________ ________________________



On the other hand, I noticed that the definition of the boundary condition in the baffle patch of the T file (also in the other variables) is quite diferent from one case to the other. Let's see the difference.

1. My case (it seems like it's been copied directly from the createBafflesDict file)
   

       baffleFacesThermoBaffle3D_master
       {
           type            compressible::thermalBaffle;
           kappa           fluidThermo;
           kappaName       none;
           regionName      baffle3DRegion;
           active          yes;
           thermoType
           {
               type            heSolidThermo;
               mixture         pureMixture;
               transport       constIso;
               thermo          hConst;
               equationOfState rhoConst;
               specie          specie;
               energy          sensibleEnthalpy;
           }
           mixture
           {
               specie
               {
                   nMoles          1;
                   molWeight       20;
               }
               transport
               {
                   kappa           0.01;
               }
               thermodynamics
               {
                   Hf              0;
                   Cp              15;
               }
               equationOfState
               {
                   rho             80;
               }
           }
           radiation
           {
               radiationModel  opaqueSolid;
               absorptionEmissionModel none;
               scatterModel    none;
           }
           extrudeModel    linearNormal;
           nLayers         50;
           expansionRatio  1;
           columnCells     false;
           linearNormalCoeffs
           {
               thickness       0.02;
           }
           value           uniform 300;
       }

2. Tutorial case (It has been generated from the createBafflesDict file, but not directly copied)
   

       baffleFacesThermoBaffle3D_master
       {
           type            compressible::thermalBaffle;
           refValue        uniform 300;
           refGradient     uniform 0;
           valueFraction   uniform 1;
           value           uniform 300;
           Tnbr            T;
           QrNbr           none;
           Qr              none;
           thicknessLayers 0();
           kappaLayers     0();
           kappa           fluidThermo;
           kappaName       none;
           extrudeModel    linearNormal;
           nLayers         10;
           expansionRatio  1;
           columnCells     0;
           linearNormalCoeffs 
           {
               thickness       0.05;
           }
   
           regionName      baffle3DRegion;
           active          1;
           thermoType      
           {
               type            heSolidThermo;
               mixture         pureMixture;
               transport       constIso;
               thermo          hConst;
               equationOfState rhoConst;
               specie          specie;
               energy          sensibleEnthalpy;
           }
   
           mixture         
           {
               specie
               {
                   nMoles          1;
                   molWeight       20;
               }
               transport
               {
                   kappa           0.01;
               }
               thermodynamics
               {
                   Hf              0;
                   Cp              15;
               }
               equationOfState
               {
                   rho             80;
               }
           }
   
           radiation       
           {
               radiationModel  opaqueSolid;
               absorptionEmissionModel none;
               scatterModel    none;
           }
   
       }

You can see the differences deeper by checking the files attached if you need it.

________________________________3rd Question________________________________

· Is this error related to the previous one? Is it really an error? Why is it occurring?

__________________________________________________ ________________________


As you can see I am having strong problems and I don't know what to do next because, as I already said, I have been trying to figure out what is going wrong for a few days with no success. That's why now I really need some help to go forward with my case. I'm sure that the problem is something obvious, or even ridiculous, but I haven't been able to solve it by myself so far. So if anybody has a hint or advice I will be very grateful to read it.

Many thanks in advance.


Alex

PS: My apologies for the size of the text