Spanwise domain effects on streamwise vortices in the plane turbulent mixing layer

McMullan, W. A.

doi:10.1016/j.euromechflu.2017.10.007

Cited by 7 publications

(6 citation statements)

References 39 publications

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“…The data grid was systematically decimated to create two additional levels of grid resolution in each direction The spanwise direction is of particular interest due to the collection method this study is attempting to validate and reinforce. Spanwise turbulent features are an important mode for convection of primitives in any flow and any simulation that doesn't properly resolve the span will produce poor turbulent statistics [48]. With the HSC integrating features along the line-of-sight, it is especially important to be able to say with accuracy what effect the turbulence has on the span, and that enough of the large eddies are resolved that the turbulence is correctly representative of the real flow.…”

Section: Grid Convergence Resultsmentioning

confidence: 99%

Large Eddy Simulation of Three Dimensional Wall Effects in a Scramjet Cavity Flameholder

Oren¹,

Komives²,

Peterson

2018

2018 Fluid Dynamics Conference

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Section: Grid Convergence Resultsmentioning

confidence: 99%

Large Eddy Simulation of Three Dimensional Wall Effects in a Scramjet Cavity Flameholder

Oren¹,

Komives²,

Peterson

2018

2018 Fluid Dynamics Conference

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“…On both grids the upper and lower walls of the domain are modelled as slip walls. The spanwise boundaries are periodic, and the spanwise domain extent is sufficiently large that the flow is not artificially confined by the periodicity (McMullan 2015(McMullan , 2018b. The outflow condition is of a standard convective form.…”

Section: Simulation Parametersmentioning

confidence: 99%

Large eddy simulation of the variable density mixing layer

2021

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In this paper we perform large eddy simulations of variable density mixing layers, which originate from initially laminar conditions. The aim of this work is to capture the salient flow physics present in the laboratory flow. This is achieved through varying the nature of the inflow condition, and assessing the vortex structure present in the flow. Two distinct inflow condition types are studied; the first is an idealised case obtained from a mean inflow velocity profile with superimposed pseudo-white-noise, and the second is obtained from an inflow generation technique. The inflow conditions generated have matching mean and root mean squared statistics. Validation of the simulations is achieved through grid dependency and subgrid-scale model testing. Regardless of the inflow condition type used, the change in growth rate of the mixing layer caused by the density ratio is captured. It is found that the spacing of the large-scale spanwise structure is a function of the density ratio of the flow. Detailed interrogation of the simulations shows that the streamwise vortex structure present in the mixing layer depends on the nature of the imposed inflow condition. Where white-noise fluctuations provide the inflow disturbances, a spatially-stationary streamwise structure is absent. Where the inflow generator is used, a spatially stationary streamwise structure is present, which appears as streaks in plan-view visualisations. The stationary streamwise structure evolves such that the ratio of streamwise structure wavelength to local vorticity thickness asymptotes to unity, independent of the density ratio. This value is in agreement with previous experimental studies. Recommendations are made on the requirements of inflow condition modelling for accurate mixing layer simulations.

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“…Geometric expansions are used to stretch the grids in both of these directions, in order to reduce the cell count in regions of low flow variability. The spanwise grid spacing is constant, with a value of z = 4.7 × 10 −3 m. Grids of comparable resolution have been shown to produce reliable mixing layer simulation results [39,40], and the spanwise domain extent is sufficient to avoid artificial confinement of the mixing layer [34,36]. The grid is well-refined, when compared to other studies of the high Reynolds number mixing layer [29].…”

Section: Simulation Setupmentioning

confidence: 99%

Mixing and combustion at low heat release in large eddy simulations of a reacting shear layer

Huang

McMullan

2021

Theor. Comput. Fluid Dyn.

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In this paper, the mixing and combustion at low-heat release in a turbulent mixing layer are studied numerically using large eddy simulation. The primary aim of this paper is to successfully replicate the flow physics observed in experiments of low-heat release reacting mixing layers, where a duty cycle of hot structures and cool braid regions was observed. The nature of the imposed inflow condition shows a dramatic influence on the mechanisms governing entrainment, and mixing, in the shear layer. An inflow condition perturbed by Gaussian white noise produces a shear layer which entrains fluid through a nibbling mechanism, which has a marching scalar probability density function where the most probable scalar value varies across the layer, and where the mean-temperature rise is substantially over-predicted. A more sophisticated inflow condition produced by a recycling and rescaling method results in a shear layer which entrains fluid through an engulfment mechanism, which has a non-marching scalar probability density function where a preferred scalar concentration is present across the thickness of the layer, and where the mean-temperature rise is predicted to a good degree of accuracy. The latter simulation type replicates all of the flow physics observed in the experiment. Extensive testing of subgrid-scale models, and simple combustion models, shows that the WALE model coupled with the Steady Laminar Flamelet model produces reliable predictions of mixing layer diffusion flames undergoing with fast chemistry.

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Spanwise domain effects on streamwise vortices in the plane turbulent mixing layer

Cited by 7 publications

References 39 publications

Large Eddy Simulation of Three Dimensional Wall Effects in a Scramjet Cavity Flameholder

Large Eddy Simulation of Three Dimensional Wall Effects in a Scramjet Cavity Flameholder

Large eddy simulation of the variable density mixing layer

Mixing and combustion at low heat release in large eddy simulations of a reacting shear layer

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