Learning Forum

[martina.mohr]

Hello, I’m trying to simulate a heatsink cooling in air with the Fluid-Solid Heat Transfer Simulation. Therefore I have two regions: 1.    Fluid Flow, Thermal Physics Region 1 – for the air surrounding the heat sink 2.    Thermal Physics Region 2 – for the solid body of the heatsink itself (Within this Region 2 there are several different material assignments) When I use the Region Interface Generator, it only generates an Interface between some faces within the Thermal Physics Region 2.   I cannot get it to generate the interface between the air and the solid body. Every time I add a new Region Interface Generator it generates the same interface within the solid body Region over and over again. What do I have to change for it to also generate the Interface between the fluid and the solid body?   Thanks in advance!

[Naresh Patre]

Hello M_Mohr

Can you cross check if you have correctly assigned bodies to the 2 physics regions?

Can you try changing the tolerance value in region interface generator and see if that helps? If not, I will have to look at the geometry to investigate the issue. Will it be possible to attach the model here? (note that any attachment will be public and can be viewed by all forum users)

 

[martina.mohr]

Naresh Patre 

 

Hi, 

I checked the assigned bodies to the regions and they seem to be correct to me.

I also tried changing the tolerance and now there is a second Interface generated between the solid Body and the fluid Region, but it is still not the result I'm looking for. 

 

Unfortunately, I'm not allowed to share the model here on the Forum, but if you could contact me via email, I can send it to you that way. 

 

Thank you for your help!

[Naresh Patre]

Hello Martina_Mohr

I will contact you through email.

[Naresh Patre]

Hello Martina_Mohr

The file which you have uploaded is an incomplete file and cannot be opened. You need to send the project folder too. Alternatively, you can archive the entire project file which will create a single file with extension .wbpz which you can send. Details on file archiving are mentioned in this post.

[martina.mohr]

Hello Naresh , 

sorry about that! I tried to reupload using archived files.

[Naresh Patre]

Hello Martina_Mohr

You are right, the solid bodies need to be cut from the fluid domain for generating region interface. Interfaces are generated between overlapping faces. If there are no overlapping faces between the 2 physics regions, there won't be any region interface generated.

Secondly, if you look at the "Region Interface Generator" there is a message saying that several faces are candidates for more than one region interface. See below snapshot. This means that one face is a part of multiple overlapping regions. All such faces get ignored in region interface generation. That is why the region interface generated between thermal physics region is showing only a few interfaces.

 

To overcome this issue, you need to spit faces where bodies are touching each other. The quickest way to achieve this is by imprinting. To do this, go to Geometry task and edit the geometry. In Modeling window, go to Prepare tab and click "Imprint" tool. This will highlight all the possible locations in the model. Click the "Complete" button to complete the operation and create imprints. Once done, close the modeling session. Go to flow task and delete already created region interfaces. Now regenerate the region interfaces using the interface generator. You should now see several interfaces within the thermal physics region.

[martina.mohr]

Hi Naresh , 

 

thank you for this advice! I do not longer get the message that faces are candidates for multiple interfaces. It can’t seem to solve one of the problems, but the simulation seems to accept it anyway.  

 

But how do I now add all the solid thermal conditions I need? As soon as I add a heat flow it says that the face has been reused. Which I see, because it is selected for the heat flow as well as for the region interface, but does that mean that I can't use the automatic interface generator? Even if I redo the generator it still selects the faces that I already used for the heat flow conditions.

I'm sorry I'm having such a hard time understanding this.

[Naresh Patre]

Hello Martina_Mohr

You can add Heat Source (Volumetric heat source) from solid thermal conditions and select one or more bodies in your physics region where you would like to include the heat source.

[martina.mohr]

Hello Naresh , 

 

alright it works now. Thank you so much for your help!