My thoughts exactly.
To my aging mind, the "velocity scale" and a fluids "viscosity" will be directly related to one another.
So my "viscosity_scale" allows the programmer to "tweak" those values at the same time.
A higher viscosity_scale means that either the terrain is a large body of "water",
or a small body of a "thicker" fluid.

Would you guys agree with this? Play with the viscosity value with what Ive already posted to see what I mean if need be.