DNS of droplet-laden homogeneous shear turbulence

We have studied the effects of droplets on the evolution of incompressible homogeneous shear turbulence (HST) via direct numerical simulation (DNS). We performed DNS of droplet-laden HST using a mesh of 1200 × 600 × 600 grid points for a Reynolds number based on the Taylor length-scale of turbulence (λ) at the droplets' release-time of Re_λ = 53. The flow was randomly seeded with 1260 droplets (equivalent to 5% droplet volume-fraction) of diameter approximately equal to twice λ. For the cases studied, we varied the initial Weber number based on the r.m.s. velocity of the carrier flow, We_rms, from 0.02 to 0.5 while keeping the density and viscosity ratios constant (ρ_d/ρ_c = 10 and μ_d/μ_c = 10). The results show that for We_rms = 0.02 and We_rms = 0.5, the production of turbulence kinetic energy (TKE) is larger and smaller than that of the droplet-free case, respectively, and that increasing We_rms causes a decrease in TKE production. We explain the modulation due to the droplets of TKE production and power of the surface tension, respectively, through the droplet "catching-up" and the droplet "shearing" mechanisms.