Hydrodynamic boundary layer near strongly retarded bubble surface

Hydrodynamic Boundary Layer near Strongly Retarded Bubble Surface and 

In contrast to free bubble surfaces, the role of boundary layers for the strong or complete retardation of a bubble surface is of substantial interest. Levich (1962), who introduced the notion of the hydrodynamic potential field of bubbles in the absence of surfactant pointed out that the velocity drop across the boundary layer is small. For completely or strongly retarded surfaces, the velocity distribution beyond the hydrodynamic boundary layer is a potential one. 

The role of lift-forces F, (Safman, 1965) in flotation has been raised by Mileva (1990) but it is considered under conditions most unfavourable for F,. Schulze (1992) draws attention to a possible neglecting of F, as shown by Clift et al. (1978). Some remarks addressing the part of Mileva s work (1990) concerning lift-forces are given in Appendix lOM. 

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