Turbulence modification by dispersion of large deformable droplets

Dispersion of large deformable droplets in turbulent channel flow is investigated: the fluids are considered of same density and viscosity for a broad range of plausible values of surface tension. Droplets much larger than the Kolmogorov length scale are released in a channel flow; the turbulent flow is computed with pseudo-spectral Direct Numerical Simulations (DNS), while phase interactions are described with a Phase Field Model (PFM). It is shown that droplets segregation toward the center of the channel is promoted by deformability in particular, for the considered Weber numbers (ratio between inertia and surface tension), droplets do not deposit on the walls. The turbulent flow is modified by the presence of the droplets: for small values of We the wall drag is increased with respect to the single phase flow. The wall drag enhancement reduces increasing We and its time evolution depends on the droplets coalescence and breakup rates.