Problem with boundary conditions
 

Hi!,
I am working on my thesis, and I need to know how to add the following boundary conditions to OpenFoam:

a * <grad(C) , n> + b * C * <grad(V) , n> = 0

where
a and b are constants
C and V are scalar fields
n is the normal vector to the boundary surface
< , > is the scalar product
grad() is the gradient

Thank you!!

Emmanuel