How to add external time varying force
 

Hi,

I am dealing with a self-developed bc for movingwall motion. I calculate forces on the moving boundary using forces utility. Now, I want to add external force to the 'forces' calculated by foam utility. This external force is a time varying quantity. I want my bc to make use of the vector sum of these forces at each time step.

so, I want to add external force to the forces calculated by foam utility.
Could someone help me out ?

thanks,