Mixing, scalar boundedness, and numerical dissipation in large-eddy simulations

Abstract

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights • Methods to enforce scalar boundedness in incompressible-flow simulations are proposed. • Mixing metrics sensitive to the additional numerical dissipation are identified. • Numerical-dissipation effects on mixing in large-eddy simulations are assessed. • Performance of the proposed methods is examined for the first time by mixing metrics.

Turbulent shear-layer mixing: initial conditions, and direct-numerical and large-eddy simulations

“…Flows examined in this paper are temporally evolving counter-flow turbulent shear layers, in a domain of length , and periodic boundary conditions in all three directions (Matheou & Dimotakis 2016; Sharan et al. 2018 a ). The domain extent is .…”

“…To mitigate this problem, the monotonicity-preserving method discussed in Sharan et al. (2018 a ) is used at global scalar bounds.…”

“…The flow configuration was described previously (Matheou & Dimotakis 2016; Sharan et al. 2018 a ), with Cartesian coordinates denoting the streamwise, spanwise and cross-stream directions, respectively, and denoting the corresponding velocity components. The (molecular diffusivity) Schmidt number is set to unity, , approximating gas-phase diffusion in all simulations.…”

“…In particular, considering that mixing occurs at the smallest scales, numerical and model errors can lead to erroneous predictions of mixed-fluid composition and scalar fluctuations (e.g. Sharan, Matheou & Dimotakis 2018 a ).…”

Investigation of high-pressure turbulent jets using direct numerical simulation

“…Turbulent free-shear flow computations are sensitive to the choices of initial/inflow conditions, domain size and numerical discretization (Balaras, Piomelli & Wallace 2001; Mattner 2011; Sharan, Matheou & Dimotakis 2018 a ). In particular, several experimental (e.g.…”