Aerodynamic forces on a Bluff Body (a Sphere)

Relevant parameters:

• free-stream velocity, U

• diameter of the sphere, D

• density of the fluid, r

• viscosity of the fluid, m

• forces on the sphere, FL & FD

FL = 0 because of symmetry

FD = f(U,D,r,m)

To carry out a set of experiments to characterize the drag forces on spheres, one need to vary four parameters independently: U,D,r,m.

• It is very time consuming and the resulting data set will be difficult to analyze.

• Some kinds of scaling are needed to apply the wind tunnel testing data to a real flow problem.

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