Is the dot small enough that you can approximate it as a single point source of uniform intensity at least?
Regardless, Flow doesn't do motion (which would make it easy to have a moving source), so the only way I see is to define a bunch of sources with time dependence.
If it's a surface source in W/m2 then you can define the watt density based on x, y, z, and time - can you resolve it into a single equation?
The dot is a distribution over a diameter of 7.5 inches, so no. This is not in flow simulation, just in the transient thermal module. I see no way in the transient thermal simulation module (not flowworks) to define the heat flux based on coordinates and time. THe only opitons I see are "use time curve" and "use temperature curve"