3. Two Models for the Drag Force

Our approximations for CD in Section 2.3 allow us to derive two formulas for the drag force, FD. Recall from Section 1.2 that FD is


  fdeqn

where f is the function relating the Reynolds number to the drag coefficient. The log-log plot of f was created in Section 2.1.

3.1 The drag force for Re < 0.5

3.2 The drag force for 10^3 < Re < 10^5

Thus, depending on the Reynolds number, the drag force, FD, can be proportional to either v or to v^2.

Up to The Drag Force on a Sphere