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A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenTue, 16 Apr 2024 16:11:20 +0000The Stretched-Vortex SGS Model in Physical Space
https://resolver.caltech.edu/CaltechAUTHORS:20200714-123705635
Authors: {'items': [{'id': 'Voelkl-T', 'name': {'family': 'Voelkl', 'given': 'T.'}}, {'id': 'Pullin-D-I', 'name': {'family': 'Pullin', 'given': 'D. I.'}}, {'id': 'Henderson-R-D', 'name': {'family': 'Henderson', 'given': 'R. D.'}}]}
Year: 1999
DOI: 10.1007/978-94-011-4513-8_39
The stretched-vortex subgrid stress model for the large-eddy simulation of turbulent flows has been developed to the stage where it can be applied to realistic flow at large Reynolds numbers [1] [2]. The basic assumption of this model [3] is that the subgrid vortex structure consists of straight, stretched vortices containing a nearly axisymmetric subgrid vorticity field. Vortices of this type, such as the Burgers vortex and the stretched-spiral vortex have provided fair quantitative estimates of turbulence fine-scale properties [4]. These structures are probably an oversimplified model of fine-scale turbulence, but may nevertheless contain sufficient of the vortex-stretching and energy cascade physics characteristic of the small scales to provide a reasonable basis for subgrid-stress modelling for LES. The resulting subgrid stresses are
Τ_(ij)=K(δ_(ij)−e^v_ie^v_j).
(1)
where K is the subgrid energy and e_i^ v , i = 1, 2, 3 are the direction cosines of the subgrid vortex axis. The local subgrid dissipation ϵ_(sgs) is equal to the product of K with the component of S_(ij) aligned with the vortex axis. A class of simple models is obtained when it is assumed that the subgrid vortices are aligned with the eigenvectors of the rate-of-strain tensor S_(ij) [1]. Utilizing an assumed Kolmogorov form for the local subgrid energy spectrum, the model estimates the turbulent energy production at the resolved-scale cutoff in terms of the model parameters ϵ and the Kolmogorov prefactor K₀ and adjusts these parameters locally so as to continue the cascade through the cutoff to the subgrid vortex structures where the dissipation takes place.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ftxb1-71311A physical-space version of the stretched-vortex subgrid-stress model for large-eddy simulation
https://resolver.caltech.edu/CaltechAUTHORS:VOEpof00
Authors: {'items': [{'id': 'Voelkl-T', 'name': {'family': 'Voelkl', 'given': 'Tobias'}}, {'id': 'Pullin-D-I', 'name': {'family': 'Pullin', 'given': 'D. I.'}}, {'id': 'Chan-Daniel-C', 'name': {'family': 'Chan', 'given': 'Daniel C.'}}]}
Year: 2000
DOI: 10.1063/1.870429
A physical-space version of the stretched-vortex subgrid-stress model is presented and applied to large-eddy simulations of incompressible flows. This version estimates the subgrid-kinetic energy required for evaluation of the subgrid-stress tensor using local second-order structure-function information of the resolved velocity field at separations of order the local cell size. A relation between the structure function and the energy spectrum is derived using the kinematic assumptions of the stretched-vortex model for locally homogeneous anisotropic turbulence. Results of large-eddy simulations using this model are compared to experimental and direct numerical simulation data. Comparisons are shown for the decay of kinetic energy and energy spectra of decaying isotropic turbulence and for mean velocities, root-mean-square velocity fluctuations and turbulence-kinetic energy balances of channel flow at three different Reynolds numbers.https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cq7y4-20j79