1.1 The nature of fluid flow past a sphere

Changing the parameters listed above can have a significant effect on the nature of the fluid flow past a sphere. Figure 1 shows the flow field for water flowing to the right past a 2 cm diameter sphere. At very low velocities (Figure 1a), the downstream flow lines are a mirror image of the upstream flow lines. At slightly higher velocities (Figure 1b), a wide wake
forms behind the sphere. At high velocities (Figure 1c), a thin layer of turbulence forms around the sphere and the wake, now narrower, also contains some turbulence. The fluid within the wake becomes more turbulent as the velocity increases.

Figure 1:

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