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-   -   Heat flux through a device (http://www.cfd-online.com/Forums/star-ccm/95145-heat-flux-through-device.html)

Reunion December 7, 2011 11:33

Heat flux through a device
 
Hi,

I wish to model a block (say a 3d cube) and would like to get the heat flux through the center of the block. I have one side at 350K and ambient is at 325K.

I want to find the heat flux from the center of the block so I could replace the 350K temperature constraint with a heat flux in the center of the object. Anyone have any ideas?

abdul099 January 2, 2012 20:45

I'm struggling to understand your problem. What is the "heat flux from the center of the block"? The heat flux through a cross section of the block? If so, use a plane section. If not, please give more information.

Reunion January 3, 2012 07:30

Quote:

Originally Posted by abdul099 (Post 337600)
I'm struggling to understand your problem. What is the "heat flux from the center of the block"? The heat flux through a cross section of the block? If so, use a plane section. If not, please give more information.

I have tried using a plane section, however in star-ccm there are no options for obtaining heat flux, there is an option for boundary heat flux which would be the outside boundary to ambient and doesn't monitor the heat flux through the center of the block

shaunakpai January 3, 2012 18:12

Arbitrary Section to calculate heat flux.
 
In surface repair tool, using polygon patch, create a section where you want to calculate the flux (Make Sure you modify this as a different surface). Later, right click the surface in the parts tree and say "Create New Part from Surfaces". Export this part as .stl extension. Then, go to derived parts -> Create New -> Arbitrary Section and then browse to your .stl file. This will create and arbitrary section. Now go to reports and create a "Heat Transfer" report and in properties window, add the arbitrary section that you have just created and plug in the desired units. You can now run this report at the end of analysis to see the heat transfer. Also, if you want want to monitor the heat transfer while the analysis is running, you can right click the report and select create monitor and plot from report. This should solve your problem. Let me know if anything is unclear.

Reunion January 17, 2012 12:45

shaunakpai,

Thanks for your reply. I have tried to use the repair surface tool (by right clicking on the part in geometry and clicking repair surface) to create a section, however one I click ploygon patch (technically fill polygon patch) I am unable to move the screen, making a plane section hard to obtain. Once I created the plane section, I was unable to create the section and export it.

Am I following your instructions correctly?
Would you be able to be a little clearer?

Regards

Reunion

shaunakpai January 17, 2012 13:21

You are on the right track. You have to set your view such that you can create the polygon patch in one go without moving the screen. If the geometry is complicated and you are unable to do it one go, use multiple polygon patches. to complete it. Just make sure you modify all the patches to the same boundary.
You dont have to create a plane section. Ones you create the patch (or patches). Close the surface repair tool. Go to the leaf part where the new surface is located. Right click on it and select "Create Part from Surface". You can now export this new part as .stl
Let me know if you encounter any further difficulties.

Reunion January 18, 2012 06:39

Is it possible to use the offset function in repair surface tool to move the surface in a tiny bit create a surface and export it and then move it back to it's original geometry? Then import it and obtain the heat flux?

shaunakpai January 18, 2012 11:35

I don't understand the reason why you want to use the offset tool but its very easy. If you want to offset a surface, just select all the faces on the surface and then in the drop down menu, select offset faces. Then enter the direction and distance you want to move the surface. Note: The original surface will move in this case and not duplicate.

If you want multiple sections at different locations to monitor your heat flux, you don't have to export and import it. You can simply right click on the part and select duplicate. Then you can offset each of these copies to the location you want them to be at.


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