# How to calculate electrical potential with UDS?

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July 4, 2012, 22:13
How to calculate electrical potential with UDS?
#1
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Bruce
Join Date: Jul 2012
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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
Attached Images
 contact resistance.jpg (7.8 KB, 47 views)

 July 5, 2012, 01:14 #2 Super Moderator     Alex Join Date: Jun 2012 Location: Germany Posts: 3,344 Rep Power: 45 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.

July 5, 2012, 02:04
#3
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Bruce
Join Date: Jul 2012
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Quote:
 Originally Posted by flotus1 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.

 Tags contact resistance, electrical potential, uds