Influence of internal intermittency on drop breakage and coalescence in turbulent liquid-liquid dispersion
Session: Intermittency and scaling 3
Session starts: Wednesday 26 August, 10:30
Presentation starts: 10:30
Room: Room H
Wioletta Podgorska (Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warsaw, Poland)
Break-up and coalescence of droplets in stirred dispersion is considered and the influence of highly intermittent nature of turbulence on scale-up is discussed. Drop breakup occurs when disruptive stresses overcome the stabilizing ones. Three different situations are taken into account: (a) pure liquid-liquid system with dispersed phase of low viscosity in which the only disruptive stress is due to pressure fluctuations and stabilizing stress is due to interfacial tension, (b) pure system with dispersed phase of high viscosity in which viscous stress generated within the drop increases stabilizing effect, (c) system with surfactant and additional disruptive stress. In all cases internal intermittency causes faster breakage in larger scale when average energy dissipation rate in the tank is maintained. Additionally, for system (a) coalescence was taken into account. In this system drop interfaces are partially mobile and coalescence is faster in larger scale due to intermittency.