A direct numerical simulation study of interface propagation in homogeneous turbulence

Abstract

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 $S_{L}$ to the r.m.s. turbulent velocity $U^{\prime }$ and various (50, 100 and 200) turbulent Reynolds numbers$\mathit{Re}$. 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$U^{\prime }/S_{L}$and$\mathit{Re}$, (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$U^{\prime }/S_{L}$and$\mathit{Re}$, (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.