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Các bài báo tiêu biểu
A dynamic subgrid-scale eddy viscosity modelOne major drawback of the eddy viscosity subgrid-scale stress models used in large-eddy simulations is their inability to represent correctly with a single universal constant different turbulent fields in rotating or sheared flows, near solid walls, or in transitional regimes. In the present work a new eddy viscosity model is presented which alleviates many of these drawbacks. The model co... ... hiện toàn bộ
Tập 3 Số 7 - Trang 1760-1765 - 1991
A proposed modification of the Germano subgrid-scale closure methodThe subgrid-scale closure method developed by Germano et al. is modified by use of a least squares technique to minimize the difference between the closure assumption and the resolved stresses. This modification removes a source of singularity and is believed to improve the method’s applicability.
Tập 4 Số 3 - Trang 633-635 - 1992
Development of turbulence models for shear flows by a double expansion techniqueTurbulence models are developed by supplementing the renormalization group (RNG) approach of Yakhot and Orszag [J. Sci. Comput. 1, 3 (1986)] with scale expansions for the Reynolds stress and production of dissipation terms. The additional expansion parameter (η≡SK̄/■̄) is the ratio of the turbulent to mean strain time scale. While low-order expansions appear to provide an adequate descript... ... hiện toàn bộ
Tập 4 Số 7 - Trang 1510-1520 - 1992
A dynamic subgrid-scale model for compressible turbulence and scalar transportThe dynamic subgrid-scale (SGS) model of Germano et al. [Phys. Fluids A 3, 1760 (1991)] is generalized for the large eddy simulation (LES) of compressible flows and transport of a scalar. The model was applied to the LES of decaying isotropic turbulence, and the results are in excellent agreement with experimental data and direct numerical simulations. The expression for the SGS turbulent ... ... hiện toàn bộ
Tập 3 Số 11 - Trang 2746-2757 - 1991
Preferential concentration of particles by turbulenceDirect numerical simulation of isotropic turbulence was used to investigate the effect of turbulence on the concentration fields of heavy particles. The hydrodynamic field was computed using 643 points and a statistically stationary flow was obtained by forcing the low-wave-number components of the velocity field. The particles used in the simulations were time advanced according to Stokes... ... hiện toàn bộ
Tập 3 Số 5 - Trang 1169-1178 - 1991
A dynamic mixed subgrid-scale model and its application to turbulent recirculating flowsThe dynamic subgrid-scale eddy viscosity model of Germano et al. [Phys. Fluids A 3, 1760 (1991)] (DSM) is modified by employing the mixed model of Bardina et al. [Ph.D dissertation, Stanford University (1983)] as the base model. The new dynamic mixed model explicitly calculates the modified Leonard term and only models the cross term and the SGS Reynolds stress. It retains the favorable fe... ... hiện toàn bộ
Tập 5 Số 12 - Trang 3186-3196 - 1993
Subgrid-scale backscatter in turbulent and transitional flowsMost subgrid-scale (SGS) models for large-eddy simulations (LES) are absolutely dissipative (that is, they remove energy from the large scales at each point in the physical space). The actual SGS stresses, however, may transfer energy to the large scales (backscatter) at a given location. Recent work on the LES of transitional flows [Piomelli et al., Phys. Fluids A 2, 257 (1990)] has shown... ... hiện toàn bộ
Tập 3 Số 7 - Trang 1766-1771 - 1991
Spectral features of wall pressure fluctuations beneath turbulent boundary layersExperimental measurements of the frequency spectra and frequency cross-spectra of the wall pressure fluctuations beneath a turbulent boundary layer were made in a low-noise flow facility. The data, taken over a range of flow speeds, clearly display a dimensionless frequency (ωδ/uτ=50) at which the spectra achieve a maximum and a low-frequency range with an approximately ω2 rolloff. The sca... ... hiện toàn bộ
Tập 3 Số 10 - Trang 2410-2420 - 1991
Modeling of the deformation of a liquid droplet impinging upon a flat surfaceThis article presents a theoretical study of the deformation of a spherical liquid droplet impinging upon a flat surface. The study accounts for the presence of surface tension during the spreading process. The theoretical model is solved numerically utilizing deforming finite elements and grid generation to simulate accurately the large deformations, as well as the domain nonuniformities ... ... hiện toàn bộ
Tập 5 Số 11 - Trang 2588-2599 - 1993
Local energy transfer and nonlocal interactions in homogeneous, isotropic turbulenceDetailed computations were made of energy transfer among the scales of motion in incompressible turbulent fields at low Reynolds numbers generated by direct numerical simulations. It was observed that although the transfer resulted from triad interactions that were nonlocal in k space, the energy always transferred locally. The energy transfer calculated from the eddy-damped quasinormal Ma... ... hiện toàn bộ
Tập 2 Số 3 - Trang 413-426 - 1990