Discussion Forum

Hello,everyone.I was trying to solving a problem which is concerned with the flux of ionic species under the electrical and concentration field.Basically,I want to find out the local concentration of the ions at the bond pad-moulding
compound interface.
The mass flux is given by the equation J1=-D*(grad(C1)*(1+q*C1/(1-C1*q))+grad(U)*(F*C1/R*T)
where C1 denotes the concentration of the species,
J denotes the flux of ion species
U denotes electric field,
D denotes diffusion coefficient
T denotes the temperature
q,F,R is a constant
My model is rectanglar with mounding compoud in the upper part and Al pad in the lower part,left side and right side of the rectangular are set to 1Voltage and -1Voltage,respectively.Upper and lower sides are set 0Voltage.All the boundary are set to be electrical insulating.Temperature T, diffusion coefficient D,C1,,q,F,R are all given.

My first question is the coefficient PDE model seems like doesn't match my equation above,Because according to the template of coef PDE model,J is a source term,which doesn't make sence.Is it correct that I modified the equation to this form grad(J1)=0=grad(-D*(grad(C1)*(1+q*C1/(1-C1*q))+grad(U)*(F*C1/R*T)) so that I can match the template?

My second qustion is do I need to create two cofficient PDE model in order to express the electric field and concentration field separately?

I attached the reference paper if you are willing to see it in details.

I have been stucked in this problem for more than 1 month.
I will be appreciate if you could help me out
!!!