2006 Rayleigh-Taylor driven mixing in a multiply stratified environment

Mixing is ubiquitous in both the natural environment and industrial applications, and its consequences are far-reaching. This paper focuses on the details of the small scale mixing processes which are driven by buoyancy in a gravitational field. In particular we explore the evolution of an interleaved heavy-light-heavy miscible liquid system with one Rayleigh-Taylor unstable density interface, and one statically stable interface. Experiments are performed using LIF illumination of a chemically reactive but dynamically passive tracer, and we seek to quantify mixing induced across both interfaces. In a complementary numerical study, adaptive mesh refinement is used to target computational capacity at the small scales in the region surrounding the stable density interface. It is of particular interest whether simulations accurately capture mixing across stable density interfaces in liquid systems, when frequently such codes operate with Schmidt numbers of order unity. 1