Effects of burning on the development of 2D turbulence

Abstract

We present the results of two-dimensional (2D) direct numerical simulations of a Boussinesq fluid in the presence of gravity. Our simulations compare the evolution of a burning interface between a denser fuel and less dense ashes to the evolution of a non-burning interface. Initially, a dense, cool fluid is placed over a light, hot fluid and the interface between the two fluids is perturbed. Because of the presence of gravity, the system is Rayleigh–Taylor unstable, and the two fluids mix. We compare this Rayleigh–Taylor mixing problem to that in the same setup but with premixed combustion occurring at the interface between the two fluids. In both cases, the boundary conditions are periodic in the horizontal direction. As the force of gravity is increased, the flow behind the flame transitions from an ordered, laminar state to a chaotic, turbulent state. Our simulations explore the effect of burning on the development of the turbulent state, especially the effect of burning on the energy and enstrophy cascades, the mixing of the temperature fields and the shape of the flame front.