Spectral Filtering a Model Reactive Tracer; Implications for Large Eddy Simulations

This talk will examine the application of several spectral filters to a reactive, passive tracer field from a direct numerical simulation. The tracer reacts according to an idealized non-linear reaction and is subjected to three-dimensional turbulent mixing induced by a Rayleigh-Taylor instability. The mathematical procedure required to obtain the sub-filter-scale advection and reaction quantities from the advection-diffusion-reaction equation governing the reactive tracer evolution will be briefly presented. Each of the sub-filter-scale quantities can be considered in terms of contributions from resolved-scale, cross-scale, and sub-filter-scale interactions. These contributions are quantified for various spectral filter choices and the implications for modelling reactive tracers will be discussed.