I am trying to figure out what “momentum source” actually does.

I have read these two pages:

but none of them provide any formulae that would help figure out how the input “mean velocity” is represented in the Navier Stokes equations.

Let’s say I assign a “momentum source” to a box and provide a desired mean velocity.

I assume that the “momentum source” feature then computes a mass-specific force F required to achieve that the velocity averaged in the box equals the user-input mean velocity.

I assume that this mass-specific force is imposed at every location inside this box, F thus being constant in space within the box.

*What I actually need is a means of assigning a mass- or volume-specific force that is than added to the right-hand side of the Navier-Stokes equations.*

*This does not seem to be implemented though.*

Is this correct?

Thanks.