KINETICS OF STRUCTURE DEVELOPMENT IN LIQUID-LIQUID DISPERSIONS UNDER SIMPLE SHEAR-FLOW - THEORY

The kinetics of structure development in a moderately concentrated liq uid-liquid dispersion under the hydrodynamic conditions of simple shea r flow has been analyzed using differential population balance equatio ns. The existing models of the breakup and coalescence phenomena have been examined, modified, and included in the population balances to th e extent necessary. It was found that in the present range of drop siz es and viscosity ratios the temporal evolution of the average drop siz e is primarily determined by drop breakup rather than by coalescence. It was further shown that the evolution of the size distribution funct ion as well as the average drop size are strong functions of the visco sity ratio, exhibiting sharp changes at the critical capillary number. The role of the initial drop size distribution on the time-dependent state of the dispersion was examined, including the path leading to a bimodal distribution. (C) 1996 Society of Rheology.