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Solving 3 PDEs simultaneously. Require help in defining the PDEs

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I need to solve 3 PDEs simultaneously. I am facing problems designing those PDEs. Kindly help. I am attaching an excerpt of a paper which has all the info. I am trying to solve eqns 4,5,6 of the paper.

So the problems I am facing are:

1. In PDE 1 which is a derived form of the continuity equation for drift-diffusion, I have a dependent variable u1 which needs to be solved for, but the equation also includes variable u2 which will be the dependent variable for PDE2. Also u2= -grad(E) where E is the electric potential. So how do I define u2 and how do i write the gradient of electric field.

2. So when matching the co-efficients of my PDE to the co-efficient form PDE , the diffusion co-efficient C is matched to ion diffusivity i.e. D but the units dont match, so it is showing an error.
Also how do I represent div and grad in the parameters if i need to define them manually.

Thank you for your help.


0 Replies Last Post 17 dic 2016, 06:55 GMT-5
COMSOL Moderator

Hello Paritosh Sahu

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