Mass Addition
 

I am having a geometry that resembles a normal rectangle. The walls; upper wall and the lower walls (which are the walls running along the length of the rectangle) are to given with the condition of adding mass to it. How is it possible in Fluent? Or should i opt for some other Code? And if it's possible in Fluent what should i do to apply it?

Source terms are just available in volumes. But you can use boundary conditions at faces for importing a mass to your domain.

Thanks for your consideration and reply sir.

But I am dealing with only the 2D geometry and not 3D. In that case where can I find the options for the Mass Addition or I am looking for the Moving Boundary itself.

You can just use boundary condition for importing mass the your domain. Source terms are used just for inside of the domain not the faces around.