I want to solve the following equations:$\frac{{\partial n_D(T)}}{\partial t } = \nabla. (D\nabla n_D(T) -vn_D(T) )=0$where $D$ is the diffusion constant, $v$ is the velocity and $n_D(T$ is the concentration.$-\nabla .\kappa_{th} \nabla T =\sigma |\nabla\psi|^2$ where $T $is the temperature, $\sigma (n_D, T)$ conductivity, $\kappa(n_D, T)$ thermal conductivity.I am using dilute species and Joule heating modules to solve these equations. I can't couple them together. The coupling was done by copying the solution and then changing  initial values of variables Solved for for in the dependent variables option of the solver 1. After solving thing I don't get any electric field or potential in solution. Could you please advise me ?
Coupling Equations in COMSOL
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