The local wavenumber model for computation of turbulent mixing

Abstract

We present an overview of the current status in the development of a two-point spectral closure model for turbulent flows, known as the local wavenumber (LWN) model. The model is envisioned as a practical option for applications requiring multi-physics simulations in which statistical hydrodynamics quantities such as Reynolds stresses, turbulent kinetic energy, and measures of mixing such as density-correlations and mix-width evolution, need to be captured with relatively high fidelity. In this review, we present the capabilities of the LWN model since it was first formulated in the early 1990s, for computations of increasing levels of complexity ranging from homogeneous isotropic turbulence, inhomogeneous and anisotropic single-fluid turbulence, to two-species mixing driven by buoyancy forces. The review concludes with a discussion of some of the more theoretical considerations that remain in the development of this model. This article is part of the theme issue ‘Scaling the turbulence edifice (part 2)’.

Non-locality of mean scalar transport in two-dimensional Rayleigh–Taylor instability using the macroscopic forcing method

“…For example, two-point closures to account for non-locality in RTI have been developed by several authors for RANS (Clark & Spitz 1995; Steinkamp, Clark & Harlow 1999 b , a ; Pal et al. 2018; Kurien & Pal 2022) and LES (Parish & Duraisamy 2017). While these works attempt to address the effects of non-locality in RTI, they do so without directly studying the form of the non-local operator.…”

“…(1) a density gradient, (2) an acceleration (associated with the body force) in the direction opposite to that of the density gradient, and (3) a perturbation at the interface of the two fluids. RTI is present in many scientific and engineering applications, such as supernovae Pal et al 2018;Kurien & Pal 2022) and LES (Parish & Duraisamy 2017). While these works attempt to address the effects of non-locality in RTI, they do so without directly studying the form of the non-local operator.…”