Direct numerical simulation of turbulent Couette flow with immiscible droplets

A direct numerical simulation has been carried out in order to clarify the effects of the high viscosity and the interfacial tension of a droplet on the interaction between the droplet and near-wall turbulence. A liquid turbulent plane Couette flow with an immiscible droplet of the same fluid density as that of the: continuous-phase has been used. The diameter of the droplet is fixed at one-fourth of the wall distance. which is nearly equal to 41 wall units. The droplet has been assigned in the range of 20-60 wall units from one moving wall initially. The modified volume of fluid (VOF) algorithm and local grid refinement are used for tracking the phase interface. The velocities for the fine grid are decided so that the equation of continuity is satisfied in the fine cell. It is found that the deformation of the droplet due to the surrounding fluid Row is suppressed by the effect of the interfacial tension of the droplet. The streamwise vortex is attenuated by the existence of the droplet with the interfacial tension. The small vortex is generated in the wake region of the droplet. The Reynolds-shear stress product becomes higher in a wide region around the droplet. (C) 2001 Elsevier Science Inc. All rights reserved.