Figure 5.

The RPM rotation introduces fluid motion in the culture flask, leading to shear forces and enhanced convection. Therefore, a moderate rotational velocity needs to be chosen, and the velocity transitions have to be smooth in order to minimize the introduction of additional mechanical stimulation of the samples. In this numerical illustration, the fluid motion is shown if both frames rotate at 60 deg/s. This results in a periodic motion of 6 seconds. The four images indicate snapshots of the velocity at 0 s (a), 1.2 s (b), 2.2 s (c), and 4 s (d).