Heat transfer in drop-laden turbulent channel flow

Abstract

In this work, we study the heat transfer between a dispersed phase of large deformable drops and a carrier fluid in wall-bounded turbulence. We perform a campaign of direct numerical simulations of the Navier Stokes equations, coupled with a Phase Field Method, which describes the behavior of the dispersed phase and coupled with the energy equation, which takes into account the heat transport. We consider a system in which drops are free to deform, break and coalesce, while heat is exchanged between the two phases and the two walls. Several values of Weber number (We, ratio of inertial forces to surface tension forces) and Prandtl number (Pr, ratio of momentum diffusivity to thermal diffusivity) are evaluated, while the shear Reynolds and the volume fraction are fixed. First, we characterize the dispersed phase dynamics by analyzing the coalescence and breakage dynamics of the drops and the corresponding drop size distribution. Second, we investigate the role of the drops internal flow in the modulation of heat transport. In particular, we analyze the characteristics of the flow structure inside the drops and we study how turbulent mixing influences the rate with which heat is diffused inside the drops, and transferred across the interface of the drop towards the carrier fluid.