[intied]

Hi.
I am computing a source term of the energy equation in ANSYS Fluent.
How to add a system of differential equations in a UDF?
Each differential equation depends on time and temperature.
In particular, I want to solve a set of differential equations based on the Arrhenious equation:
dx1/dt=k1*exp(k2/(R*T)),
dx2/dt=k3*exp(k4/R*T),

where k1,k2,k3,k4 and R are constants. Thus, my source term is (dx1/dt+dx2/dt)*k5.

I know that I could use DEFINE_SOURCE(name,c,t,dS,eqn).
Any suggestion?

Regards