Barleywine
That is an extraordinarily lucid and helpful way of looking at the effects of reversals (and I'm glad I remember enough high school physics to know what a Venturi tube is
It also dovetails nicely with one of the ways I tend to look at reversals already: as a means of the reversed card saying that the issue it's describing has to be dealt with whether we're comfortable with it or not.
And I seem to have forgotten my industrial application knowledge. Constricting the flow increases the upstream pressure of the fluid, thus increasing its stored potential energy. I changed my earlier post to add the "too-tight pair of shoes" analogy.