stokes problem is:

sphere radius r, falling in viscous liquid under gravity.

variables are: v,r,g, , , . dimensions are this means 6-3 = 3 dimensionless variables. , =Frued's number, =Reynolds number. This means: . Using the fact that a terminal velocity will appear, assume . This means . B.C. suggest

In the limit reynolds number 1, you get: ,

in another convention. . This is the correct limit for a rain drop falling in the air.

For a human, .

For spheres in corn syrup, from experimental data.

source psfile jl@crush.caltech.edu index buckingham_pi_theorem