HELP！How to define this kind of inlet concentration in transient solver?
 

Dear all,

I run a transient simulation of species transport, and the concentration of each species at the flow inlet should be prescribed according to the following relation:

dc_in/dt = A*(c_out - c_in),

where A is a constant, c_in and c_out are the average values of concentration at the inlet and outlet boundary. How to write this kind of relation (dc_in/dt = ...) in UDF?

Thand you very much!

Jack