source term in transport equation
 

Dear all,
I am doing one phase modeling of a settling column.

I am trying to define a convective flux (div($$SettlingVelocity*${Passive Scalar}*$Density)) through the source term of the passive scalar ( in my case passive scalar is the solid fraction).

$$SettlingVelocity is a field function that depends on ${Passive Scalar}.

Is it possible to define it as a convection term the way they do it in Fluent? like: dot($$SettlingVelocity,$$Area)*$DensityUser

I get this error that the field function can not be calculated on the cells of the region.