BREAKAGE AND COALESCENCE MODELS FOR DROPS IN TURBULENT DISPERSIONS

A substantial effort has been made by numerous investigators to descri be droplet breakage and coalescence in turbulent dispersions. An attem pt is made here to improve these models based on existing frameworks a nd recent advances described in the literature. Two-step mechanisms ar e considered for both the breakage and coalescence models. The drop br eakage function is structured as the product of the drop-eddy collisio n frequency and breakage efficiency which reflect the energetics of tu rbulent liquid-liquid dispersions. The coalescence function retains th e former structure of the product of drop-drop collision frequency and coalescence efficiency. The coalescence efficiency model has been mod ified to account for the effects of film drainage for drops with parti ally mobile interfaces. These models overcome several inconsistencies observed in previous efforts and are applicable for dense dispersions (about phi[0.10-0.30]). For the daughter drops produced by breakage, a probability density is proposed based on the energy requirements for the formation of daughter drops.