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The shear sensitivity of animal and plant cells is a problem often encountered in large-scale cell culture. Such sensitivity varies with different cell lines and the severity of cellular damage may depend on both the magnitude and the duration of the shear stress. In a bioreactor, the shear susceptibility of cells depends on their response to hydrodynamic forces arising from fluid motions of particular scale. Cell damage may be induced by forces in the bulk liquid phase, but fluid motions associated with the gas-liquid interface are especially energetic. The detrimental effects of hydrodynamic forces are abated by the addition of some polymers, such as Pluronic F-68, methylcellulose, or serum; the exact mechanisms of protection are the subject of current research.

Photographic observation of the disintegration of individual flocs upon interaction with a turbulent jet has been used to quantify the binding force of kaolin‐polymer and kaolin‐Fe+III aggregates. The data suggest that the strength per unit mass decreases with increasing floc size, thereby supporting the multiple‐level model for aggregation.

The population balance equation coupled with the proposed breakage kernel and the previously developed breakage model is applied to the analysis of bubble size distribution for non-coalescing systems in a bench-scale airlift column. Good agreement obtained between the theoretical results and the experimental data is encouraging and indicates that the model is suitable for predicting dispersion properties such as bubble size and interfacial area in turbulent gas-liquid dispersions.

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