Anisotropic Heat and Mass Transport Induced by Droplet-Scale Hydrodynamics of Multiphase Flows under Shear

The heat and mass transport characteristics of a shear-driven multiphase flow with single and multiple droplets have been numerically studied over a wide range of parameters. The heat and mass exchange between the dispersed droplets and the continuous fluid and heat and mass transport within the mixture have been considered. In the presence of flow shear, interface tension at the droplet surface constrains droplet shearing and generates a microscale recirculating flow inside and outside the droplet. The flow recirculation works as a micro mixer, which enhances the heat and mass transport. When the droplet size is large and surface tension cannot resist the tearing of flow shear stress, the droplets deform greatly and even break up. The deformation and breakup impose a complex transient hydrodynamic effect on heat and mass transfer around the droplets. When the volume fraction of the dispersed droplets is large, the contact and non-contact interactions among the neighboring droplets will affect the behaviors of each droplet and cause disturbances in the continuous fluid. The disturbances also enhance heat and mass transport in the system. This research offers promising potential for the precise control of the heat and mass transfer in multiphase flows.