On the relevance of the type of contraction of the Germano identity in the new integral-based dynamic Smagorinsky model

2013 ◽  
Vol 72 ◽  
pp. 30-45 ◽  
Author(s):  
Filippo Maria Denaro
Keyword(s):  
Smagorinsky Model ◽  
Germano Identity

Reduction of the Germano-identity error in the dynamic Smagorinsky model

2009 ◽  
Vol 21 (6) ◽  
pp. 065106 ◽  
Author(s):  
Noma Park ◽  
Krishnan Mahesh
Keyword(s):  
Smagorinsky Model ◽  
Germano Identity

Robust dynamic adaptation of the Smagorinsky model based on a sub-grid activity sensor

2021 ◽  
Vol 33 (1) ◽  
pp. 015117
Author(s):  
J. Hasslberger ◽  
L. Engelmann ◽  
A. Kempf ◽  
M. Klein
Keyword(s):  
Dynamic Adaptation ◽  
Smagorinsky Model ◽  
Model Based

A hybrid dynamic Smagorinsky model for large eddy simulation

2020 ◽  
Vol 86 ◽  
pp. 108698
Author(s):  
Qingxiang Shui ◽  
Cuie Duan ◽  
Xinyi Wu ◽  
Yunwei Zhang ◽  
Xilian Luo ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Smagorinsky Model ◽  
Eddy Simulation ◽  
Large Eddy

Assessment of turbulence models using DNS data of compressible plane free shear layer flow

2021 ◽  
Vol 931 ◽  
Author(s):  
D. Li ◽  
J. Komperda ◽  
A. Peyvan ◽  
Z. Ghiasi ◽  
F. Mashayek
Keyword(s):  
Shear Layer ◽  
Compressible Flows ◽  
Eddy Viscosity ◽  
Turbulence Models ◽  
Correlation Coefficients ◽  
Free Shear Layer ◽  
Smagorinsky Model ◽  
Reynolds Analogy ◽  
Velocity Fluctuations ◽  
Scale Similarity

The present paper uses the detailed flow data produced by direct numerical simulation (DNS) of a three-dimensional, spatially developing plane free shear layer to assess several commonly used turbulence models in compressible flows. The free shear layer is generated by two parallel streams separated by a splitter plate, with a naturally developing inflow condition. The DNS is conducted using a high-order discontinuous spectral element method (DSEM) for various convective Mach numbers. The DNS results are employed to provide insights into turbulence modelling. The analyses show that with the knowledge of the Reynolds velocity fluctuations and averages, the considered strong Reynolds analogy models can accurately predict temperature fluctuations and Favre velocity averages, while the extended strong Reynolds analogy models can correctly estimate the Favre velocity fluctuations and the Favre shear stress. The pressure–dilatation correlation and dilatational dissipation models overestimate the corresponding DNS results, especially with high compressibility. The pressure–strain correlation models perform excellently for most pressure–strain correlation components, while the compressibility modification model gives poor predictions. The results of an a priori test for subgrid-scale (SGS) models are also reported. The scale similarity and gradient models, which are non-eddy viscosity models, can accurately reproduce SGS stresses in terms of structure and magnitude. The dynamic Smagorinsky model, an eddy viscosity model but based on the scale similarity concept, shows acceptable correlation coefficients between the DNS and modelled SGS stresses. Finally, the Smagorinsky model, a purely dissipative model, yields low correlation coefficients and unacceptable accumulated errors.

scholarly journals Comparative Study of Standard Smagorinsky Model and Dynamic Smagorinsky Model in Large Eddy Simulation of Turbulent Channel Flow

2020 ◽  
Vol 12 (1) ◽  
pp. 39-53
Author(s):  
M. S. I. Mallik ◽  
M. A. Hoque ◽  
M. A. Uddin
Keyword(s):  
Large Eddy Simulation ◽  
Comparative Study ◽  
Channel Flow ◽  
Flow Simulation ◽  
Turbulent Channel Flow ◽  
Smagorinsky Model ◽  
Order Accuracy ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Contour Plots

This paper presents results of comparative study of large eddy simulation (LES) that is applied to a plane turbulent channel flow. The LES is performed by using a finite difference method of second order accuracy in space and a low-storage explicit Runge-Kutta method with third order accuracy in time. In the LES for subgrid-scale (SGS) modelling, Standard Smagorinsky Model (SSM) and Dynamic Smagorinsky Model (DSM) are used. Essential turbulence statistics from the two LES approaches are calculated and compared with those from direct numerical simulation (DNS) data. Comparing the results throughout the calculation domain, it has been found out that SSM performs better than DSM in the turbulent channel flow simulation. Flow structures in the computed flow field by the SSM and DSM are also discussed and compared through the contour plots and iso-surfaces.

scholarly journals Performance of the Finite Element and Finite Volume Methods for Large Eddy Simulation in Homogeneous Isotropic Turbulence

2010 ◽  
Vol 2 (2) ◽  
pp. 237-249 ◽  
Author(s):  
M. A. Uddin ◽  
C. Kato ◽  
N. Oshima ◽  
M. Tanahashi ◽  
T. Miyauchi
Keyword(s):  
Finite Element ◽  
Large Eddy Simulation ◽  
Finite Volume ◽  
Isotropic Turbulence ◽  
Finite Volume Methods ◽  
Homogeneous Isotropic Turbulence ◽  
Smagorinsky Model ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Better Than

Large eddy simulation (LES) in homogeneous isotropic turbulence is performed by using the Finite element method (FEM) and Finite volume vethod (FVM) and the results are compared to show the performance of FEM and FVM numerical solvers. The validation tests are done by using the standard Smagorinsky model (SSM) and dynamic Smagorinsky model (DSM) for subgrid-scale modeling. LES is performed on a uniformly distributed 643 grids and the Reynolds number is low enough that the computational grid is capable of resolving all the turbulence scales. The LES results are compared with those from direct numerical simulation (DNS) which is calculated by a spectral method in order to assess its spectral accuracy. It is shown that the performance of FEM results is better than FVM results in this simulation. It is also shown that DSM performs better than SSM for both FEM and FVM simulations and it gives good agreement with DNS results in terms of both spatial spectra and decay of the turbulence statistics. Visualization of second invariant, Q, in LES data for both FEM and FVM reveals the existence of distinct, coherent, and tube-like vortical structures somewhat similar to those found in instantaneous flow field computed by the DNS. Keywords: Large eddy simulation; Validation; Smagorinsky model; Dynamic Smagorinsky model; Tube-like vortical structure; Homogeneous isotropic turbulence. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.DOI: 10.3329/jsr.v2i2.2582              J. Sci. Res. 2 (2), 237-249 (2010) 

Aerodynamic Noise Simulation of Propeller Fan by Large Eddy Simulation

2007 ◽  
Author(s):  
Shingo Hamada ◽  
Seiji Nakashima ◽  
Chisachi Kato ◽  
Yoshinobu Yamade
Keyword(s):  
Large Eddy Simulation ◽  
Pressure Rise ◽  
Tip Vortex ◽  
Aerodynamic Noise ◽  
Blade Surface ◽  
Frequency Range ◽  
Smagorinsky Model ◽  
Measured Velocity ◽  
Eddy Simulation ◽  
Large Eddy

In this paper, unsteady flow and aerodynamic noise are numerically investigated for a half-open type propeller fan used for outdoor air conditioner components. The flow field is calculated by Front Flow/Blue, which is based on Large Eddy Simulation (LES). The Standard Smagorinsky Model (SSM) and Dynamic Smagorinsky Model (DSM) were used as sub-grid scale models. Aerodynamic noise was calculated by Curle’s equation based on the pressure fluctuation on the blade surface computed by LES. The computed static pressure rise of the fan showed reasonable agreement with the measured equivalent. The time-averaged distributions of the three velocity components downstream of the blades were also compared with those measured by hotwire anemometry, which showed satisfactory agreement between the computed and measured velocity profiles. But the tip vortex passage which was detached from the blade surface predicted by LES was not stable as measured by the experiment. Finally, the predicted far-field sound spectrum agrees reasonably well with measurements in a frequency range of 100 to 1000 Hz although the sound pressure level was underpredicted in the lower frequency range.

scholarly journals Enstrophy Cascade and Smagorinsky Model of 2D Turbulent Flows

2001 ◽  
Vol 17 (3) ◽  
pp. 121-129
Author(s):  
Mei-Jiau Huang
Keyword(s):  
Reynolds Number ◽  
Large Eddy Simulation ◽  
Turbulent Flows ◽  
Smagorinsky Model ◽  
Large Wave ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Wave Numbers ◽  
Enstrophy Cascade ◽  
Stretching Effect

ABSTRACTDirect numerical simulations of 2D turbulent flows, freely decaying as well as forced, are performed to examine the mechanism of the enstrophy cascade and serve as a template of developing LES models. The stretching effect on the 2D vorticity gradients is emphasized on the analogy of the stretching effect on 3D vorticity. The enstrophy cascade rate, the Reynolds stresses and the associated eddy viscosity for 2D turbulence are correspondingly derived and investigated. Proposed herein is that the enstrophy cascade rate to be modeled in a large-eddy simulation can be and should be calculated using the only available large-eddy information, especially when the Reynolds number is not very large or when the flow is not stationary.The simulation results suggest all Kolmogorov's, Kraichnan's, and Saffman's similarity spectra. The Kolmogorov's spectrum appears in front of forced wave numbers and creates a subrange of a zero enstrophy cascade rate and a constant energy cascade rate. The Saffman's spectrum is the dissipation spectrum at large wave numbers. Kraichnan's spectrum shows up at intermediate wave numbers when the Reynolds number is sufficiently high. When the Smagorinsky model is employed for a large eddy simulation, its inability of capturing the significant reverse cascade phenomenon as observed in the DNS data becomes a fatal defect. Nonetheless, if only the mean cascade rate is concerned, the required Smagorinsky constant is evaluated using the DNS data and compared with the theoretical prediction of the Kraichnan's spectrum.

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