Reactive Rayleigh-Taylor Turbulence

Abstract

The Rayleigh-Taylor (RT) instability develops and leads to turbulence when a heavy fluid falls under the action of gravity through a light one. We consider this phenomenon accompanied by a reactive transformation between the fluids, and study with Direct Numerical Simulations (DNS) how the reaction (flame) affects the turbulent mixing in the Boussinesq approximation. We discuss "slow" reactions where the characteristic reaction time exceeds the temporal scale of the RT instability. In the early turbulent stage, effects of the flame are distributed over a maturing mixing zone, whose development is weakly influenced by the reaction. At later times, the fully mixed zone transforms into a conglomerate of pure-fluid patches of sizes proportional to the mixing zone width. In this "stirred flame'' regime, temperature fluctuations are consumed by reactions in the regions separating the pure-fluid patches. This DNS-based qualitative description is followed by a phenomenology suggesting that thin turbulent flame is of a single-fractal character, and thus distribution of the temperature field is strongly intermittent.

14 pages, 4 figures

References in corpus (5)

• Thermonuclear Supernovae: Simulations of the Deflagration Stage and Their Implications
• On the miscible Rayleigh-Taylor instability: two and three dimensions
• Three-dimensional Numerical Simulations of Rayleigh-Taylor Unstable Flames in Type Ia Supernovae
• Self-Similarity and Universality in Rayleigh-Taylor, Boussinesq Turbulence
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Cited by in corpus (5)

• Rayleigh-Taylor Unstable Flames -- Fast or Faster?
• Modeling and Simulation of Transitional Rayleigh-Taylor Flow with Partially-Averaged Navier-Stokes Equations
• Evolution of a double-front Rayleigh-Taylor system using a GPU-based high resolution thermal Lattice-Boltzmann model
• Rayleigh-Taylor unstable flames at higher Reynolds number
• Rayleigh-Taylor Unstable Flames: the Effect of Two-Mode Coupling