Figure 2.

Steady flow of a viscous fluid at very low Reynolds numbers (“creeping flow”) past a glass microbubble. (a) The flow lines are shown in a planar section parallel to the flow direction and passing through the center of the microbubble. Coordinates for description of the theoretical distribution of velocity in flow past a microbubble are also shown. (b) The force diagram of a glass microbubble-cell complex with the internal action-reaction force also shown. (c) A plot shows the dependence of the volume of fluid searched per microbubble per unit time, Q (the solid line), as well as Q_n′, Q normalized to the cross-sectional area per microbubble (the dashed line), to the diameter of the microbubble. (d) A plot shows the dependence of the maximum shear stress (the dashed line) and the action-reaction force, F_act (the solid line), to the diameter of the microbubble.