A direct numerical simulation study of interface propagation in homogeneous turbulence

A 3D direct numerical simulation (DNS) study of the evolution of a self-propagating interface in forced constant-density statistically stationary homogeneous isotropic turbulence was performed by solving Navier–Stokes and level-set equations under a wide range of conditions that cover various (from 0.1 to 2.0) ratios of the interface speed SL to the r.m.s. turbulent velocity U′ and various (50, 100 and 200) turbulent Reynolds numbers Re. By analysing computed data, the following issues were addressed: (i) dependence of the speed and thickness of the fully developed statistically planar mean front that envelops the interface on U′/SL and Re, (ii) dependence of the fully developed mean turbulent flux of a scalar c that characterizes the state of the fluid (c=0 and 1 ahead and behind the interface respectively) on U′/SL and Re, (iii) evolution of the mean front speed, its thickness, and the mean scalar flux during the front development after embedding a planar interface into the forced turbulence and (iv) relation between canonical and conditioned moments of the velocity, velocity gradient and pressure gradient fields.