Flow around balls, circles, cylinders, etc.

The following examples concern flows, mostly through channels, around a set of obstacles, as for instance circles and balls.

Right after the obstacle(s), the flow separates and produces complex flow patterns, oscillating in space and time. In many applications, the corresponding drag and lift forces acting on the obstacle(s) are of major interest, and a difficult numerical job to do! The complexity of the problem depends on the:

• inflow speed
• rotational speed of the obstacles
• viscosity
• size and distance of the obstacles, w.r.t. to the channel walls and to each other

A systematic variation of these different configurations is part of the following flow situations:

• The `DFG-Benchmark 1995/6': Channel flow around a circle at Re=100
• Flow around a volleyball at a medium Reynolds number (study of the influence of the spin of a volleyball by students)
• Flow around a volleyball at a larger medium Reynolds number (study of the influence of the spin of a volleyball by students)