Net heat flow not same as total heat flux 1

[toohotforme]

Hi I’m not totally familiar with ANSYS. I want to find a way to compute the net (total) heat flow rather than the discrete steps of heat flow that match a mesh.

In the example a copper rod has a constant temp. applied at each end (200C one end and 93C at other). Convection heat transfer coeff. is known and so is the ambient temp.
Calculating; one can integrate the heat flux along the surface to arrive at a total Watts of heat loss.

How does one derive this figure by modelling?

One has Watts/m2 for discrete elements … The attached jpg shows the current stage of the model.
Thanks %-)

 

[toohotforme]

I think it is the Reaction Probe function selecting the appropriate surface and the convection boundary condition.

 

[flash3780]

Interestingly enough, I'm dealing with a similar problem in Workbench. The reaction probe is the appropriate means of outputting net heat crossing a convective or temperature boundary.

Unfortunately, I don't think that it is possible to output the net heat crossing a conductive (contact or continuously meshed surface) boundary in Workbench. This may be possible with APDL scripting and command objects as well, but my APDL skills are limited so I use a different approach.

What I've done is output the nodal flux components along the desired boundary, taken the dot product of the heat flux vectors and the vectors the surface normals, and computed the surface integral in Matlab. It's not the prettiest methodology, but it should get you an answer.

From the look of your model, you might be okay using the reaction probe in the GUI, but if you need the heat passing through a conductive boundary post-processing or APDL scripting might be necessary.

 

[toohotforme]

Thanks flash3780 - I was thinking of an approach along those lines. Don't have nor am I familiar with Matlab - maybe I need to...

 

[flash3780]

These days I use Octave instead of Matlab. Octave has most of the functionality of Matlab, but is available for free from the GNU project. I've found that it runs best on Linux, but is available for Windoze as well.

 

[toohotforme]

Thanks for that suggestion! Very kind of you to share that tip!

I will look for that.

Cheers!