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-   -   How to calculate electrical potential with UDS? (http://www.cfd-online.com/Forums/fluent/104202-how-calculate-electrical-potential-uds.html)

 seagullor July 4, 2012 22:13

How to calculate electrical potential with UDS?

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Hi everyone,

I an trying to solve electrical potential by using user defined scalar transport equations in FLUENT. Just as the JPEG, the left side (of A) has the high electrical potential and the right side (of B) has the low electrical potential. The electrical conductivity (1/ohm-m) of different metals (A and B) are different, so the potential distribution will NOT be a straight line and there will be a angle at the contact face.

If there is CONTACT RESISTANCE (ohm-m^2) between A and B, the potential distribution will have a potential jump at the contact face. So the QUESTION is that how to set the boundary condition to take the contact resistance into account. If have to write a UDF file, how to write the code?

Any help is appreciated!
Many Thanks

Bruce

 flotus1 July 5, 2012 01:14

You might exploit the analogy between electric and thermal conduction.

electric potential -> Temperature
current -> conductive heat flux

Set up your case as a heat transfer problem, there you have all the tools built-in that you need (different conductivities, contact resistance...)

I think this will get you further than a UDS.

 seagullor July 5, 2012 02:04

Quote:
 Originally Posted by flotus1 (Post 369856) You might exploit the analogy between electric and thermal conduction. electric potential -> Temperature current -> conductive heat flux Set up your case as a heat transfer problem, there you have all the tools built-in that you need (different conductivities, contact resistance...) I think this will get you further than a UDS.
Many thanks!

YES, I've thought about the analogy before! But the problem need to consider both the temperature (ohmic heat) and the electric potential, so I have to add UDS in my fluent case.

Another question: UDS seems to breaks for porous (fluid) zone. For porous zone, the solid material's 'UDS Diffusivity' will not appear if the ENERGY EQUATION is DISABLED. After enabling the energy equation, the solid material's uds diffusivity can be modified, but the uds equation cannot be solved through the porous zone although both the fluid's and solid's uds diffusivities have been set already.

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