A tadpole (young frog) has a spherical head with a diameter of 2.5 mm and swims with a speed of 5 mm/s in a pool of dirty water that has a density 1.1 times the density of clean water and a viscosity that is 1.3 times the viscosity of clean water. To study in detail the flow around this tadpole, one researcher has built a large-scale, geometrically similar model with a head diameter of 25 mm.
a) Is it possible to make meaningful tests of the tadpole swimming using the above model i) in a wind tunnel, ii) in a water tunnel, and iii) in a towing tank filled with glycerin (all fluids at 20°C) ?
b) Now assume that tests of the model are made in a towing tank filled with glycerin. The drag force on the model is measured to be F_Dmodel. Estimate the drag force on the tadpole.

Contributed by Stavros Tavoularis, Department of Mechanical Engineering, University of Ottawa, Ottawa, Canada. Image from North American Tadpoles.