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February 16, 2018, 12:25 
UDS diffusivity for Joule Heating problem

#1 
New Member
RJC
Join Date: Jun 2015
Posts: 18
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I am trying to simulate resistive heating in fluid. I am writing a UDF for joule heating and also introducing a UDS in the model. The UDS is to solve the current continuity equation.
Grad J = Grad (Sigma Grad Phi ) sigma= electrical conductivity, Phi= Potential, Grad= Gradient and the UDF is for joule heating: q= j^2/phi I am not sure what would be the UDS diffusivity? Say my fluid has a electrical conductivity of 0.005 S/m, then what should be the UDS diffusivity here. Also, how do I define my boundary condition? My boundary condition would be an applied current density of 1e7 A/m2. How do I define that? 

February 25, 2018, 21:21 

#2  
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Alexander
Join Date: Apr 2013
Posts: 2,363
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Quote:
1. your UDS diffusivity is the same as electrical conductivity, you put it as material property. 2. you can apply current density as source. So you need to write UDF script for that 3. as boundary conditions I think you should define inlet Phi (potential) value By the way, fluent has builtin electric potential model. You may try to find how to use in in manuals ANSYS Fluent User's Guide Chapter 28: Modeling Electric Potential Field On the other hand, you may find information regarding fluent implementation of single potential battery model in ANSYS Fluent Advanced AddOn Modules file Look into Part II Chapter 2: SinglePotential Empirical Battery Model Best regards 

December 23, 2022, 06:43 
what if the current density has to be set to boundary consition

#3  
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zhubin
Join Date: Dec 2022
Posts: 8
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Quote:
As you mentioned, in the UDS function electric potential, a potential value can be set as boundary condition. I have solved the electric potential problem, but still want to add the variation of current density on the boundary. Do you have any advice? thanks a lot just set the specified flux of zone uds boundary value using udf? 

December 26, 2022, 03:38 

#4 
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Alexander
Join Date: Apr 2013
Posts: 2,363
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as far as I understand at the same boundary you may specify scalar value (potential) or flux (current density).
You should choose one of them
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