Breakage, coalescence, size distribution and heat transfer from drops in turbulence

Abstract: Existence of drops and bubbles in turbulence is granted by their interfaces, a tiny transition layer, a macroscopic perception of molecular properties. The role of interfaces is enormously important in a number of environmental and industrial processes since it is across interfaces that momentum, heat and mass transfer fluxes occur. One example for all: the amount of daily CO2 exchanged at the ocean– atmosphere depends largely on the size distribution of bubbles and drops, on the transfer coefficient across the interface and on the flow properties inside the bubbles and drops. In this talk, we will give an historical perspective of the problem and we will briefly review the modelling and computational methodologies suitable to to track interfaces. We will focus on the phase-field approach and we will present flow instances and phenomena in which surface tension, density and viscosity are varied. We will consider the interplay of the interface and the turbulence also cover the role of surfactants in altering topological changes of drops (breakage and coalescence). Finally, we will also examine heat and species transfer between a dispersed and continuous phase as a function of fluid transfer properties.