Zero heat flux through heat sink base

[Anonymous]

I have a heat sink material that is surrounded on four sides by aluminum (excluding inlet and outlet). Non-zero heat flux is on every wall except the heat sink base (where the heat source is located). Why wouldn't the heat sink base be experiencing heat flux at all?

Thanks in advance.

[Royce_adsk]

Hi @Anonymous,

Regarding the heat sink base, is there another material that is touching that surface? Could you also supply a picture of what you are seeing? It might help.

One simple tip that might be related here.  When you have two adjacent solid material that are the same material and you want to see what the heat flux between those materials, make sure that they have the same material properties, but different material names.  This will allow for the solver to know to solve for that surface.  The solver in the background will join common material surfaces to simplify the model.

[Anonymous]

Hi Royce,

The heat sink base is touching air and a fan on the other two sides. In the picture attached, the two arrows are the surfaces of thermal contact, and the heat sink base is on the left with horizontal fins.

On the top, left, and bottom side of the heat sink, CFD gives a non-zero heat flux. On the left side (aka the heat sink base), CFD gives 0W, even though it's the same two materials.

Thanks in advance.

[Royce_adsk]

Hi @Anonymous,

Can you post the share file? I would like to run and dig into the file a bit more.  If you can't post you can send via private message. 

Thank you!

[matt.bemis · Accepted solution]

There were a couple issues here. We ultimately opted for just modeling the heat sink geometry. One challenge was that the approach velocity was so high the H.S.M. was not operating in "normal" condition.

Here are some awesome resources for heat sink materials: 

http://help.autodesk.com/view/SCDSE/2017/ENU/?guid=GUID-8A3028B0-1ECB-4EE8-832F-FD165C6B3167

https://knowledge.autodesk.com/support/cfd/learn-explore/caas/CloudHelp/cloudhelp/2017/ENU/SimCFD-Us...