where n denotes the outward pointing normal of the boundary. When the mass transport includes migration of ionic species, the flux is defined as:
The flux prescribed, J0, can include any arbitrary user-specified expression. It can be constant or a function of a dependent variable or independent variable. Common examples are a flux dependent of the concentration, temperature, pressure or the electric potential
.
Set Flux type to
External convection to prescribe a flux to or from an exterior domain (not modeled) assumed to include convection. The exterior can for example include a forced convection to control the temperature or to increase the mass transport. In this case the prescribed mass flux corresponds to
where kc is a mass transfer coefficient and
cb is the bulk concentration, the typical concentration far into the surrounding exterior domain.