I understood it as you described Aleck. Sometimes analogies help explain somewhat complex ideas to people best
And unfortuantely the surface to surface contact between the materials does have a boundary layer of sorts, hence the need for thermal grease.
Sometimes I over generalize to make things simpler but yeah I got Ya
A nice flow diagram showing the actual water flow at the surface for a single jet would show people a lot I think. Flow is next to impossible to determine in your head, until it's actually plotted out.