Flux
This node can be used to specify the charge carriers flux across a boundary. The flux can, for example, occur due to chemical reactions or a phase change at the boundary.
Inward flux
Individually specify the flux for each charge carrier. Select the checkbox for the Carrier to specify the inward flux, and then enter a value or expression in the corresponding field. To use another boundary condition for a specific carrier, click to clear the checkbox for the inward flux of that carrier.
Boundary Condition for Carriers Not Specified
Specify boundary conditions other than Flux for charge carriers that were cleared above. Choose from the list: No diffusive flux, Open boundary, or No flux.