Thermal Analysis of a simple CAD file (.stl)

Dear,

I try to make a simple thermal analysis in Partial Differential Equation Toolbox. I have combine two cubes with different length in a CAD software and have export it to the format .stl . Here is the picture of the two combine cubes:

After that I mesh the model and set the temperature at Face 5 (F5) to 90°C and Face 12 (F12) to 20°C. Here is the temperature distribution. It looks like that the two cubes are not combined. What can I do that the two cubes are connected and we have a heat flow between them? In the attachment you will find the necessary files.

Thank you very much for your help. Best regards Erdal

thermalmodel = createpde('thermal','steadystate');
importGeometry(thermalmodel,'CombineCubes.stl');
pdegplot(thermalmodel, 'FaceAlpha',0.5,'FaceLabels','on','CellLabels','on')

mesh=generateMesh(thermalmodel)
pdemesh(thermalmodel);
T1 =90;
T2 = 20;

thermalProperties(thermalmodel,'cell',1,'ThermalConductivity',0.15);
thermalProperties(thermalmodel,'cell',2,'ThermalConductivity',0.3);

thermalBC(thermalmodel,'Face',5,'Temperature',T1); %Temperature upside
thermalBC(thermalmodel,'Face',12,'Temperature',T2); %Temperature downside

results = solve(thermalmodel);
pdeplot3D(thermalmodel,'ColorMapData',results.Temperature)
caxis([0 100])

[Ravi Kumar]

Hi Erdal,

Is it correct to say you want to define different thermal conductivity for each block?

What version of MATLAB are you using?

I can suggest a workflow depending on your MATLAB version.

Regards, Ravi

Answer 1

[Erdal Schranz]

Dear Ravi, thank you for your answer. I can define different thermal conductivity for each block, see in my code above

 if true 
thermalProperties(thermalmodel,'cell',1,'ThermalConductivity',0.15);  
  thermalProperties(thermalmodel,'cell',2,'ThermalConductivity',0.3);
  end

The problem is that the two blocks are not thermally connected. You can see that cause both cubes have a uniform temperature distribution. There should be a heat flow from Cube 1 to Cube 2 and therefore the temperature should not be uniform distributed. Does anybody know how to get a thermal connection between this two cubes?

Thank you

Best regards Erdal

[Fionn Mc Evoy]

did you ever find a solution to this?