Fluids

Fluids is one of my favorite subjects for sure...Shown above is the result of the last few weeks of planning and testing with some copper pipe and pumps. It was nice to see consistent results with all four curves..fun when everything lines up and you realize that you have learned something awesome!

My fluids prof saw me in the powder park line on a big (25" of 4%) day once. I said that I should be "studying fluids" to which he replied "we are about to experience some visco-elastic phenomena!"

What is the Reynold's number of a  skier fully submarined in 4% water content snow?

wiki answer:

Sphere in a fluid

For a sphere in a fluid, the characteristic length-scale is the diameter of the sphere and the characteristic velocity is that of the sphere relative to the fluid some distance away from the sphere (such that the motion of the sphere does not disturb that reference parcel of fluid). The density and viscosity are those belonging to the fluid.^[10] Note that purely laminar flow only exists up to Re = 0.1 under this definition.
Under the condition of low Re, the relationship between force and speed of motion is given by Stokes' law.

Fall velocity

The particle Reynolds number is important in determining the fall velocity of a particle. When the particle Reynolds number indicates laminar flow, Stokes' law can be used to calculate its fall velocity. When the particle Reynolds number indicates turbulent flow, a turbulent drag law must be constructed to model the appropriate settling velocity.


so Re (skier) = (450 kg/m^3 * 10m/s * 1m) / ( .01 kg/(m·s))= 450,000!


Definitely turbulent. Have fun with your own fluids research, and be sure to send me your empiracle data.