Flow classification: two-dimensional axisymmetric three-dimensional Body shape: streamlined bodies blunt bodies

Drag, D: the resultant force in the direction of the upstream velocity
Lift, L: the resultant force normal to the upstream velocity

The most important parameters are

• the Reynolds number \(\mathrm{Re}=\frac{\rho\,U\,l}{\mu}\)
• the Mach number \(\mathrm{Ma}=\frac{U}{c}\)
• the Froude number for flow with a free surface \(\mathrm{Fr}=\frac{U}{\sqrt{g\,l}}\)

Flows with $\mathrm{Re}>100$ are dominated by inertia effects, whereas flows with $\mathrm{Re} < 1 $ are dominated by viscous effects