Assing a sinusoidal body force F(x,y,z,t) in comsol 4.3

Dear all,

I am trying to simulate shear wave propagation in tissue using a PDE wave equation (I manually defined the equations).

In my geometry, I have a 3D box (imaging it is tissue) and in the center of the box (point(0,0,0)) there should be a sinusoidal force of the form:

F(x,y,z,t) = force(x,y,z)cos(2pi*df*time)

which means that at every point (xi,yi,zi) in the neighborhood of point(0,0,0) a force is applied that depends on time.

My question is how to define that in Comsol ?

what I did so far, was to define an Interpolation function force(x,y,z), where I load the values of the force at time t=0 from a txt file.
I also define a pfunction = pforce(t) = cos(2pi*df*t)

and then in the physics, I select point (0,0,0) and I assign it a Point Source, where I give it the value:

pforce(t)*force(x,y,z).

I am thinking that by this way, in every point around the center, I will be having a sinusoidal force excitation.

Does this seem correct? or if not, can you suggest another way of doing so?

Many thanks

Alexia