Journal articles: 'Lagrangian Dynamic Smagorinsky model'

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Efstathiou, G. A., R. S. Plant, and M. J. M. Bopape. "Simulation of an Evolving Convective Boundary Layer Using a Scale-Dependent Dynamic Smagorinsky Model at Near-Gray-Zone Resolutions." Journal of Applied Meteorology and Climatology 57, no. 9 (September 2018): 2197–214. http://dx.doi.org/10.1175/jamc-d-17-0318.1.

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AbstractA scale-dependent Lagrangian-averaged dynamic Smagorinsky subgrid scheme with stratification effects is used to simulate the evolving convective boundary layer of the Wangara (Australia) case study in the gray-zone regime (specifically, for grid lengths from 25 to 400 m). The dynamic Smagorinsky and standard Smagorinsky approaches are assessed for first- and second-order quantities in comparison with results derived from coarse-grained large-eddy simulation (LES) fields. In the LES regime, the subgrid schemes produce very similar results, albeit with some modest differences near the surface. At coarser resolutions, the use of the standard Smagorinsky approach significantly delays the onset of resolved turbulence, with the delay increasing with coarsening resolution. In contrast, the dynamic Smagorinsky scheme much improves the spinup and so is also able to maintain consistency with the LES temperature profiles at the coarser resolutions. Moreover, the resolved part of the turbulence reproduces well the turbulence profiles obtained from the coarse-grained fields, especially in the near gray zone. The dynamic scheme does become somewhat overenergetic with further coarsening of the resolution, especially near the surface. The dynamic scheme reaches its limit in the current configuration when the test filter starts to sample at the unresolved scales, returning very small Smagorinsky coefficients. Sensitivity tests reveal that the dynamic model can adapt to changes in the imposed numerical or subgrid diffusion by adjusting the Smagorinsky constant to the changing flow field and minimizing the dissipation effects on the resolved turbulence structures.

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Kirkil, Gokhan, Jeff Mirocha, Elie Bou-Zeid, Fotini Katopodes Chow, and Branko Kosović. "Implementation and Evaluation of Dynamic Subfilter-Scale Stress Models for Large-Eddy Simulation Using WRF*." Monthly Weather Review 140, no. 1 (January 1, 2012): 266–84. http://dx.doi.org/10.1175/mwr-d-11-00037.1.

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Abstract The performance of a range of simple to moderately-complex subfilter-scale (SFS) stress models implemented in the Weather Research and Forecasting (WRF) model is evaluated in large-eddy simulations of neutral atmospheric boundary layer flow over both a flat terrain and a two-dimensional symmetrical transverse ridge. Two recently developed dynamic SFS stress models, the Lagrangian-averaged scale-dependent (LASD) dynamic model and the dynamic reconstruction model (DRM), are compared with the WRF model’s existing constant-coefficient linear eddy-viscosity and (as of version 3.2) nonlinear SFS stress models to evaluate the benefits of more sophisticated and accurate, but also more computationally expensive approaches. Simulation results using the different SFS stress models are compared among each other, as well as against the Monin–Obukhov similarity theory. For the flat terrain case, vertical profiles of mean wind speed from the newly implemented dynamic models show the best agreement with the similarity solution, improving even upon the nonlinear model, which likewise yields a significant improvement compared to the Smagorinsky model. The more sophisticated SFS stress models more successfully predict the expected production and inertial range scaling of power spectra, especially near the surface, with the dynamic models achieving the best scaling overall. For the transverse ridge case, the nonlinear model predicts the greatest amount of reverse flow in the lee of the ridge, and also demonstrates the greatest ability to duplicate qualitative features of the highest-resolution simulations at coarser resolutions. The dynamic models’ flow distributions in the lee of the ridge did not differ significantly from the constant-coefficient Smagorinsky model.

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IIZUKA, Satoru, Shuzo MURAKAMI, Akashi MOCHIDA, Yoshihide TOMINAGA, Hikaru KOBAYASHI, and Squires K. D. "PERFORMANCE OF LAGRANGIAN DYNAMIC SMAGORINSKY MODEL : Large eddy simulation of turbulent flow past 2D square cylinder using dynamic SGS model (Part 3)." Journal of Architecture and Planning (Transactions of AIJ) 63, no. 511 (1998): 39–43. http://dx.doi.org/10.3130/aija.63.39_5.

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Pitchurov, George, Christof Gromke, Jordan A. Denev, and Flavio Cesar Cunha Galeazzo. "Validation study for Large-Eddy Simulation of Forest Flow." E3S Web of Conferences 207 (2020): 02010. http://dx.doi.org/10.1051/e3sconf/202020702010.

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The publication presents Large-Eddy Simulation (LES) of flow over a reduced-scale wind tunnel model of a forest canopy. The final aim of the study is to determine factors responsible for damage in forests by strong winds. The wind tunnel forest was represented by an open-porous foam material for the crown layer and wooden dowels for the trunk layer. The forest model was installed in the open test section of a Goettingen-type wind tunnel and Particle Image Velocimetry (PIV) measurements were made for the acquisition of the flow field data. The numerical simulations were performed with OpenFOAM®. The forest was modelled by an additional sink term in the momentum transport equations based on the leaf area density and a characteristic drag coefficient for the underlying tree specimen. Large-eddy simulations with different subgrid-scale (SGS) turbulence models were carried out and compared to wind tunnel data. The Smagorinsky SGS model outperformed the dynamic Lagrangian SGS model in the windward edge region (within a distance of approximately 2 tree heights from the leading edge) whereas the dynamic Lagrangian SGS model showed a better performance for regions farther downstream.

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Rismondo, Giacomo, Marta Cianferra, and Vincenzo Armenio. "Acoustic Response of a Vibrating Elongated Cylinder in a Hydrodynamic Turbulent Flow." Journal of Marine Science and Engineering 10, no. 12 (December 6, 2022): 1918. http://dx.doi.org/10.3390/jmse10121918.

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The present paper contains the results of the numerical analysis of the interaction between a Newtonian incompressible turbulent flow and a linear elastic slender body, together with the influence of the fluid–structure interaction (FSI) on the noise generation and propagation. The purpose is to evaluate the differences in term of acoustic pressure between the case where the solid body is rigid (infinite stiffness) and the case where it is elastic (finite stiffness). A partitioned and implicit algorithm with the arbitrary Lagrangian–Eulerian method (ALE) is used for the interaction between the fluid and solid. For the evaluation of the turbulent fluid motion, we use a large eddy simulation (LES) with the Smagorinsky subgrid scale model. The equation for the solid is solved through the Lagrangian description of the momentum equation and the second Piola–Kirchoff stress tensor. In addition, the acoustic analogy of Lighthill is used to characterize the acoustic source (the slender body) by directly using the fluid dynamic fields. In particular, we use the Ffowcs Williams and Hawkings (FW-H) equation for the evaluation of the acoustic pressure in the fluid medium. As a first numerical experiment, we analyze a square cylinder immersed in a turbulent flow characterized by two different values of stiffness: one infinite (rigid case) and one finite (elastic case). In the latter case, the body stiffness and mean flow velocity are such that they induce the lock-in phenomenon. Finally, we evaluate the differences in terms of acoustic pressure between the two different cases.

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Scotti, A., C. Meneveau, and M. Fatica. "Dynamic Smagorinsky model on anisotropic grids." Physics of Fluids 9, no. 6 (June 1997): 1856–58. http://dx.doi.org/10.1063/1.869306.

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Khani, Sina, and Michael L. Waite. "Large eddy simulations of stratified turbulence: the dynamic Smagorinsky model." Journal of Fluid Mechanics 773 (May 21, 2015): 327–44. http://dx.doi.org/10.1017/jfm.2015.249.

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The dynamic Smagorinsky model for large eddy simulation (LES) of stratified turbulence is studied in this paper. A maximum grid spacing criterion of ${\it\Delta}/L_{b}<0.24$ is found in order to capture several of the key characteristics of stratified turbulence, where ${\it\Delta}$ is the filter scale and $L_{b}$ is the buoyancy scale. These results show that the dynamic Smagorinsky model needs a grid spacing approximately twice as large as the regular Smagorinsky model to reproduce similar results. This improvement on the regular Smagorinsky eddy viscosity approach increases the accuracy of results at small resolved scales while decreasing the computational costs because it allows larger ${\it\Delta}$. In addition, the eddy dissipation spectra in LES of stratified turbulence present anisotropic features, taking energy out of large horizontal but small vertical scales. This trend is not seen in the non-stratified cases, where the subgrid-scale energy transfer is isotropic. Statistics of the dynamic Smagorinsky coefficient $c_{s}$ are investigated; its distribution is peaked around zero, and its standard deviations decrease slightly with increasing stratification. In line with previous findings for unstratified turbulence, regions of increased shear favour smaller $c_{s}$ values; in stratified turbulence, the spatial distribution of the shear, and hence $c_{s}$, is dominated by a layerwise pancake structure. These results show that the dynamic Smagorinsky model presents a promising approach for LES when isotropic buoyancy-scale resolving grids are employed.

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Schaefer-Rolffs, Urs, and Erich Becker. "Horizontal Momentum Diffusion in GCMs Using the Dynamic Smagorinsky Model." Monthly Weather Review 141, no. 3 (March 1, 2013): 887–99. http://dx.doi.org/10.1175/mwr-d-12-00101.1.

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Abstract A dynamic version of Smagorinsky’s diffusion scheme is presented that is applicable for large-eddy simulations (LES) of the atmospheric dynamics. The approach is motivated (i) by the incompatibility of conventional hyperdiffusion schemes with the conservation laws, and (ii) because the conventional Smagorinsky model (which fulfills the conservation laws) does not maintain scale invariance, which is mandatory for a correct simulation of the macroturbulent kinetic energy spectrum. The authors derive a two-dimensional (horizontal) formulation of the dynamic Smagorinsky model (DSM) and present three solutions of the so-called Germano identity: the method of least squares, a solution without invariance of the Smagorinsky parameter, and a tensor-norm solution. The applicability of the tensor-norm approach is confirmed in simulations with the Kühlungsborn mechanistic general circulation model (KMCM). The standard spectral dynamical core of the model facilitates the implementation of the test filter procedure of the DSM. Various energy spectra simulated with the DSM and the conventional Smagorinsky scheme are presented. In particular, the results show that only the DSM allows for a reasonable spectrum at all scales. Latitude–height cross sections of zonal-mean fluid variables are given and show that the DSM preserves the main features of the atmospheric dynamics. The best ratio for the test-filter scale to the resolution scale is found to be 1.33, resulting in dynamically determined Smagorinsky parameters cS from 0.10 to 0.22 in the troposphere. This result is very similar to other values of cS found in previous three-dimensional applications of the DSM.

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Schaefer-Rolffs, Urs. "A generalized formulation of the dynamic Smagorinsky model." Meteorologische Zeitschrift 26, no. 2 (April 25, 2017): 181–87. http://dx.doi.org/10.1127/metz/2016/0801.

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Wang, T., G. Tao, J. S. Bai, P. Li, and B. Wang. "Numerical comparative analysis of Richtmyer–Meshkov instability simulated by different SGS models." Canadian Journal of Physics 93, no. 5 (May 2015): 519–25. http://dx.doi.org/10.1139/cjp-2014-0099.

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The multi-mode Richtmyer–Meshkov instability is numerically simulated by the large-eddy simulation code MVFT (multi-viscous-flow and turbulence). The Vreman, dynamic Smagorinsky, and stretched-vortex models are used to model the subgrid-scale flux of turbulence transport in simulations. The calculated widths of turbulent mixing zones are all in good agreement with the experimental results, and there is a little difference among the different SGS models. However, the decay factors of turbulent kinetic energy differ significantly for different SGS models, with relative error up to about 50%. It is concluded that the dynamic Smagorinsky model and stretched-vortex model can both predict the energy backscatter, with the prediction of the former weaker, while after reshock, the dynamic Smagorinsky model is absolutely as dissipative as the Vreman model.

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Chen, Jun, Joseph Katz, and Charles Meneveau. "Implication of Mismatch Between Stress and Strain-Rate in Turbulence Subjected to Rapid Straining and Destraining on Dynamic LES Models." Journal of Fluids Engineering 127, no. 5 (June 1, 2005): 840–50. http://dx.doi.org/10.1115/1.1989360.

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Planar straining and destraining of turbulence is an idealized form of turbulence-meanflow interaction that is representative of many complex engineering applications. This paper studies experimentally the response of turbulence subjected to a process involving planar straining, a brief relaxation and destraining. Subsequent analysis quantifies the impact of the applied distortions on model coefficients of various eddy viscosity subgrid-scale models. The data are obtained using planar particle image velocimetry (PIV) in a water tank, in which high Reynolds number turbulence with very low mean velocity is generated by an array of spinning grids. Planar straining and destraining mean flows are produced by pushing and pulling a rectangular piston towards and away from the bottom wall of the tank. The velocity distributions are processed to yield the time evolution of mean subgrid dissipation rate, the Smagorinsky and dynamic model coefficients, as well as the mean subgrid-scale momentum flux during the entire process. It is found that the Smagorinsky coefficient is strongly scale dependent during periods of straining and destraining. The standard dynamic approach overpredicts the dissipation based Smagorinsky coefficient, with the model coefficient at scale Δ in the standard dynamic Smagorinsky model being close to the dissipation based Smagorinsky coefficient at scale 2Δ. The scale-dependent Smagorinsky model, which is designed to compensate for such discrepancies, yields unsatisfactory results due to subtle phase lags between the responses of the subgrid-scale stress and strain-rate tensors to the applied strains. Time lags are also observed for the SGS momentum flux at the larger filter scales considered. The dynamic and scale-dependent dynamic nonlinear mixed models do not show a significant improvement. These potential problems of SGS models suggest that more research is needed to further improve and validate SGS models in highly unsteady flows.

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Han, Shan Ling, Ru Xing Yu, Zhi Yong Li, and Yu Yue Wang. "Effect of Turbulence Model on Simulation of Vehicle Aerodynamic Characteristics Based on XFlow." Applied Mechanics and Materials 457-458 (October 2013): 1571–74. http://dx.doi.org/10.4028/www.scientific.net/amm.457-458.1571.

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The stability, comfort and safety of vehicles depend largely on the aerodynamic characteristics of the vehicle in high speed. As the turbulence model plays a decisive factor in the numerical simulation of aerodynamic characteristics, a simulation analysis of Ahmed model with a slant angle of is carried out by the XFlow software. Then the paper presents the changes of aerodynamic parameters relative to the experimental values with four turbulence models: Spalart-Allmaras model, WALE model, Dynamic Smagorinsky model and Smagorinsky model. It is found that the result of simulation with Smagorinsky model is in good agreement with experimental value, and the simulation of the wake vortex separation is consistent with the actual phenomenon. The Smagorinsky turbulence model has a good simulation precision.

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Shui, Qingxiang, Cuie Duan, Xinyi Wu, Yunwei Zhang, Xilian Luo, Chao Hong, Yuanping He, Nyuk Hien Wong, and Zhaolin Gu. "A hybrid dynamic Smagorinsky model for large eddy simulation." International Journal of Heat and Fluid Flow 86 (December 2020): 108698. http://dx.doi.org/10.1016/j.ijheatfluidflow.2020.108698.

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Mallik, M. S. I., M. A. Hoque, and M. A. Uddin. "Comparative Study of Standard Smagorinsky Model and Dynamic Smagorinsky Model in Large Eddy Simulation of Turbulent Channel Flow." Journal of Scientific Research 12, no. 1 (January 1, 2020): 39–53. http://dx.doi.org/10.3329/jsr.v12i1.41924.

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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.

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LÉVÊQUE, E., F. TOSCHI, L. SHAO, and J. P. BERTOGLIO. "Shear-improved Smagorinsky model for large-eddy simulation of wall-bounded turbulent flows." Journal of Fluid Mechanics 570 (January 3, 2007): 491–502. http://dx.doi.org/10.1017/s0022112006003429.

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A shear-improved Smagorinsky model is introduced based on results concerning mean-shear effects in wall-bounded turbulence. The Smagorinsky eddy-viscosity is modified asvT=(Csδ)2(|S|—|〈S〉|): the magnitude of the mean shear |〈S〉|is subtracted from the magnitude of the instantaneous resolved rate-of-strain tensor |S|;CSis the standard Smagorinsky constant and Δ denotes the grid spacing. This subgrid-scale model is tested in large-eddy simulations of plane-channel flows at Reynolds numbersReτ= 395 andReτ= 590. First comparisons with the dynamic Smagorinsky model and direct numerical simulations for mean velocity, turbulent kinetic energy and Reynolds stress profiles, are shown to be extremely satisfactory. The proposed model, in addition to being physically sound and consistent with the scale-by-scale energy budget of locally homogeneous shear turbulence, has a low computational cost and possesses a high potential for generalization to complex non-homogeneous turbulent flows.

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Tejada-Martı́nez, Andrés E., and Kenneth E. Jansen. "A dynamic Smagorinsky model with dynamic determination of the filter width ratio." Physics of Fluids 16, no. 7 (July 2004): 2514–28. http://dx.doi.org/10.1063/1.1738415.

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MARSTORP, LINUS, GEERT BRETHOUWER, OLOF GRUNDESTAM, and ARNE V. JOHANSSON. "Explicit algebraic subgrid stress models with application to rotating channel flow." Journal of Fluid Mechanics 639 (October 12, 2009): 403–32. http://dx.doi.org/10.1017/s0022112009991054.

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New explicit subgrid stress models are proposed involving the strain rate and rotation rate tensor, which can account for rotation in a natural way. The new models are based on the same methodology that leads to the explicit algebraic Reynolds stress model formulation for Reynolds-averaged Navier–Stokes simulations. One dynamic model and one non-dynamic model are proposed. The non-dynamic model represents a computationally efficient subgrid scale (SGS) stress model, whereas the dynamic model is the most accurate. The models are validated through large eddy simulations (LESs) of spanwise and streamwise rotating channel flow and are compared with the standard and dynamic Smagorinsky models. The proposed explicit dependence on the system rotation improves the description of the mean velocity profiles and the turbulent kinetic energy at high rotation rates. Comparison with the dynamic Smagorinsky model shows that not using the eddy-viscosity assumption improves the description of both the Reynolds stress anisotropy and the SGS stress anisotropy. LESs of rotating channel flow at Reτ = 950 have been carried out as well. These reveal some significant Reynolds number influences on the turbulence statistics. LESs of non-rotating turbulent channel flow at Reτ = 950 show that the new explicit model especially at coarse resolutions significantly better predicts the mean velocity, wall shear and Reynolds stresses than the dynamic Smagorinsky model, which is probably the result of a better prediction of the anisotropy of the subgrid dissipation.

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Su, Mingde, Qingyan Chen, and Che-Ming Chiang. "Comparison of Different Subgrid-Scale Models of Large Eddy Simulation for Indoor Airflow Modeling." Journal of Fluids Engineering 123, no. 3 (March 15, 2001): 628–39. http://dx.doi.org/10.1115/1.1378294.

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The Smagorinsky subgrid-scale model, a dynamic subgrid-scale model, and a stimulated subgrid-scale model have been used in a large eddy simulation (LES) program to compute airflow in a room. A fast Fourier transformation (FFT) method and a conventional iteration method were used in solving the Poisson equation. The predicted distributions of indoor air velocity, temperature, and contaminant concentrations show that the three subgrid-scale models can produce acceptable results for indoor environment design. The dynamic and stimulated models performed slightly better than the Smagorinsky model. The use of FFT can significantly reduce the computing time. LES is a tool of the next generation of indoor air distribution design.

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Chen, Xin, Yuan Qiang Wu, Huai Yu Wang, and Hou Yu Ning. "Applied-Information Technology with Different Sub-Grid Models in Large Eddy Simulation." Advanced Materials Research 978 (June 2014): 231–35. http://dx.doi.org/10.4028/www.scientific.net/amr.978.231.

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Aiming at different sub-grid models of large eddy simulation, numerical simulation of aerodynamic noise caused by rearview mirror was conducted by the large eddy simulation. Compared with experimental data, the results of four sub-grid models on rearview mirror simulation have the difference respectively. Studies have shown that simulation result using the Dynamic Stress Smagorinsky-Lilly model is closest to the experimental data, and the other three models have larger error. Using the Dynamic Stress Smagorinsky-Lilly model in large eddy simulation for predicting aerodynamic noise of rearview mirror is effective and feasible, which can be used as reference for subsequent rearview mirror wind noise prediction.

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Inagaki, Masahide, Tsuguo Kondoh, and Yasutaka Nagano. "A Mixed-Time-Scale SGS Model With Fixed Model-Parameters for Practical LES." Journal of Fluids Engineering 127, no. 1 (January 1, 2005): 1–13. http://dx.doi.org/10.1115/1.1852479.

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A new subgrid-scale (SGS) model for practical large eddy simulation (LES) is proposed. The model is constructed with the concept of mixed time-scale, which makes it possible to use fixed model-parameters and to dispense with the distance from the wall. The model performance is tested in plane channel flows, and the results show that this model is able to account for near-wall turbulence without an explicit damping function as in the dynamic Smagorinsky model. The model is also evaluated in a backward-facing step flow and in a flow around a circular cylinder. The calculated results using the consistent model-parameters show good agreement with experimental data, while the results obtained using the dynamic Smagorinsky model show less accuracy and less computational stability. Furthermore, to confirm the validity of the present model in practical applications, the three-dimensional complex flow around a bluff body (Ahmed et al., SAE paper no. 840300) is also calculated with the model. The agreement between the calculated results and the experimental data is quite satisfactory. These results suggest that the present model is a refined SGS model suited for practical LES to compute flows in a complicated geometry.

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Uddin, M. A., C. Kato, N. Oshima, M. Tanahashi, and T. Miyauchi. "Performance of the Finite Element and Finite Volume Methods for Large Eddy Simulation in Homogeneous Isotropic Turbulence." Journal of Scientific Research 2, no. 2 (April 26, 2010): 237–49. http://dx.doi.org/10.3329/jsr.v2i2.2582.

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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)

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Park, Noma, and Krishnan Mahesh. "Reduction of the Germano-identity error in the dynamic Smagorinsky model." Physics of Fluids 21, no. 6 (June 2009): 065106. http://dx.doi.org/10.1063/1.3140033.

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Fang, Le. "A new dynamic formula for determining the coefficient of Smagorinsky model." Theoretical and Applied Mechanics Letters 1, no. 3 (2011): 032002. http://dx.doi.org/10.1063/2.1103202.

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Ludwig, Francis L., Fotini Katopodes Chow, and Robert L. Street. "Effect of Turbulence Models and Spatial Resolution on Resolved Velocity Structure and Momentum Fluxes in Large-Eddy Simulations of Neutral Boundary Layer Flow." Journal of Applied Meteorology and Climatology 48, no. 6 (June 1, 2009): 1161–80. http://dx.doi.org/10.1175/2008jamc2021.1.

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Abstract This paper demonstrates the importance of high-quality subfilter-scale turbulence models in large-eddy simulations by evaluating the resolved-scale flow features that result from various closure models. The Advanced Regional Prediction System (ARPS) model was used to simulate neutral flow over a 1.2-km square, flat, rough surface with seven subfilter turbulence models [Smagorinsky, turbulent kinetic energy (TKE)-1.5, and five dynamic reconstruction combinations]. These turbulence models were previously compared with similarity theory. Here, the differences are evaluated using mean velocity statistics and the spatial structure of the flow field. Streamwise velocity averages generally differ among models by less than 0.5 m s−1, but those differences are often significant at a 95% confidence level. Flow features vary considerably among models. As measured by spatial correlation, resolved flow features grow larger and less elongated with height for a given model and resolution. The largest differences are between dynamic models that allow energy backscatter from small to large scales and the simple eddy-viscosity closures. At low altitudes, the linear extent of Smagorinsky and TKE-1.5 structures exceeds those of dynamic models, but the relationship reverses at higher altitudes. Ejection, sweep, and upward momentum flux features differ among models and from observed neutral atmospheric flows, especially for Smagorinsky and TKE-1.5 coarse-grid simulations. Near-surface isopleths separating upward fluxes from downward are shortest for the Smagorinsky and TKE-1.5 coarse-grid simulations, indicating less convoluted turbulent interfaces; at higher altitudes they are longest. Large-eddy simulation (LES) is a powerful simulation tool, but choices of grid resolution and subfilter model can affect results significantly. Physically realistic dynamic mixed models, such as those presented here, are essential when using LES to study atmospheric processes such as transport and dispersion—in particular at coarse resolutions.

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Dourado, Harerton Oliveira, Jane Meri Santos, Neyval C. Reis, and Ilias Mavroidis. "Numerical modelling of odour dispersion around a cubical obstacle using large eddy simulation." Water Science and Technology 66, no. 7 (October 1, 2012): 1549–57. http://dx.doi.org/10.2166/wst.2012.369.

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In the present work two different large eddy simulation (LES) approaches, namely the Dynamic Smagorinsky model and the Wale model, are used to simulate the air flow and pollutant dispersion around a cubical obstacle. Results are compared with wind tunnel data (WT) and with results from the Smagorinsky LES model. Overall agreement was good between the different LES approaches and the WT results, both for the mean and fluctuating flow and concentration patterns. LES models can provide good estimates of concentration fluctuation intensity and enable the calculation of the intermittency factor. The model results indicate that LES is a viable tool for odour impact assessment.

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O'NEIL, JOHN, and CHARLES MENEVEAU. "Subgrid-scale stresses and their modelling in a turbulent plane wake." Journal of Fluid Mechanics 349 (October 25, 1997): 253–93. http://dx.doi.org/10.1017/s0022112097006885.

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Velocity measurements using hot wires are performed across a high-Reynolds-number turbulent plane wake, with the aim of studying the subgrid-scale (SGS) stress and its modelling. This quantity is needed to close the filtered Navier–Stokes equations used for large-eddy simulation (LES) of turbulent flows. Comparisons of various globally time-averaged quantities involving the measured and modelled SGS stress are made, with special emphasis on the SGS energy dissipation rate. Experimental constraints require the analysis of a one-dimensional surrogate of the SGS dissipation. Broadly, the globally averaged results show that all models considered, namely the Smagorinsky and similarity models, as well as the dynamic Smagorinsky model, approximately reproduce profiles of the surrogate SGS dissipation. Some discrepancies near the outer edge of the wake are observed, where the Smagorinsky model slightly overpredicts, and the similarity model underpredicts, energy dissipation unless the filtering scale is about two orders of magnitude smaller than the integral length scale.A more detailed comparison between real and modelled SGS stresses is achieved by conditional averaging based on particular physical phenomena: (i) the outer intermittency of the wake, and (ii) large-scale coherent structures of the turbulent wake. Thus, the interaction of the subgrid scales with the resolved flow and model viability can be individually tested in regions where isolated mechanisms such as outer intermittency, vortex stretching, rotation, etc., are dominant. Conditioning on outer intermittency did not help to clarify observed features of the measurements. On the other hand, the large-scale organized structures are found to have a strong impact upon the distribution of surrogate SGS energy dissipation, even at filter scales well inside the inertial range. The similarity model is able to capture this result, while the Smagorinsky model gives a more uniform (i.e. unrealistic) distribution. Both dynamic Smagorinsky and similarity models reproduce realistic distributions, but only if all filter levels are contained well inside the inertial range.

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Salvo, R. V., F. J. Souza, and D. A. M. Martins. "ANALYSIS OF SUB-GRID MODELING EFFECTS IN THE SIMULATION OF THE SINGLE-PHASE TURBULENT FLOW IN AN INDUSTRIAL CYCLONE SEPARATOR." Revista de Engenharia Térmica 11, no. 1-2 (December 31, 2012): 44. http://dx.doi.org/10.5380/reterm.v11i1-2.62000.

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In the present work two turbulence modeling approaches, namely Large Eddy Simulation and Detached Eddy Simulation, are employed to predict turbulent, swirling flow within an industrial cyclone separator running at Reynolds number 267,000. The results from three LES models, Smagorinsky, dynamic and Yakhot, and the SST-DES model of Strelets have been compared to experimental results for the average axial and tangential velocities. The Navier-Stokes solver is based on an unstructured, finite volume, cell-centered algorithm such that the details of the geometry can be accurately represented. Based on the comparison with the experimental results, it has been found that the Yakhot model provides the most accurate predictions for the tangential velocities, whereas the dynamic LES and the Smagorinsky models overpredict it and the SST-DES model underpredicts it. However, the conclusions are different regarding the axial velocity. Implications of the turbulence modeling for the particle separation are discussed.

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HIRAISHI, Masayuki, and Michihisa TSUTAHARA. "Application of Dynamic Smagorinsky Model to the Finite Difference Lattice Boltzmann Method." Journal of Fluid Science and Technology 3, no. 1 (2008): 80–89. http://dx.doi.org/10.1299/jfst.3.80.

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TSUTAHARA, Michihisa, and Masayuki HIRAISHI. "Applicatoin of Dynamic Smagorinsky Model to the Finite Difference Lattice Boltzmann Method." Transactions of the Japan Society of Mechanical Engineers Series B 72, no. 719 (2006): 1659–65. http://dx.doi.org/10.1299/kikaib.72.1659.

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Wang, Bing-Chen, and Donald J. Bergstrom. "A general optimal formulation for the dynamic Smagorinsky subgrid-scale stress model." International Journal for Numerical Methods in Fluids 49, no. 12 (2005): 1359–89. http://dx.doi.org/10.1002/fld.1031.

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PORTÉ-AGEL, FERNANDO, CHARLES MENEVEAU, and MARC B. PARLANGE. "A scale-dependent dynamic model for large-eddy simulation: application to a neutral atmospheric boundary layer." Journal of Fluid Mechanics 415 (July 25, 2000): 261–84. http://dx.doi.org/10.1017/s0022112000008776.

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A scale-dependent dynamic subgrid-scale model for large-eddy simulation of turbulent flows is proposed. Unlike the traditional dynamic model, it does not rely on the assumption that the model coefficient is scale invariant. The model is based on a second test-filtering operation which allows us to determine from the simulation how the coefficient varies with scale. The scale-dependent model is tested in simulations of a neutral atmospheric boundary layer. In this application, near the ground the grid scale is by necessity comparable to the local integral scale (of the order of the distance to the wall). With the grid scale and/or the test-filter scale being outside the inertial range, scale invariance is broken. The results are compared with those from (a) the traditional Smagorinsky model that requires specification of the coefficient and of a wall damping function, and (b) the standard dynamic model that assumes scale invariance of the coefficient. In the near-surface region the traditional Smagorinsky and standard dynamic models are too dissipative and not dissipative enough, respectively. Simulations with the scale-dependent dynamic model yield the expected trends of the coefficient as a function of scale and give improved predictions of velocity spectra at different heights from the ground. Consistent with the improved dissipation characteristics, the scale-dependent model also yields improved mean velocity profiles.

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Hu, Xingjun, Peng Guo, Zewei Wang, Jingyu Wang, Mo Wang, Jia Zhu, and Dejiu Wu. "Calculation of External Vehicle Aerodynamic Noise Based on LES Subgrid Model." Energies 13, no. 7 (April 9, 2020): 1822. http://dx.doi.org/10.3390/en13071822.

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A dynamic Smagorinsky–Lilly model (DSLM) subgrid model on the basis of the Smagorinsky–Lilly subgrid model (SLM) was introduced in the OpenFOAM software. The flow field of the vehicle was simulated, and the pressure coefficient and sound pressure curve of the monitoring points were compared with the wind tunnel test results. The results show that the DSLM subgrid model with a wall function can achieve high simulation accuracy. The investigation of the flow field structure revealed an intermittent detachment of the turbulent vortex after the airflow passed through the rearview mirror, thereby resulting in a violent pressure pulsation on the side window around the rearview mirror. Airflow passed through the A-pillar, separated, and reattached on the upper side window, thereby producing aerodynamic noise. The research results can serve as a good reference for the simulation and test of aerodynamic noises outside the vehicle, and for the reduction of the aerodynamic noises of vehicles.

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CUI, G. X., C. X. XU, L. FANG, L. SHAO, and Z. S. ZHANG. "A new subgrid eddy-viscosity model for large-eddy simulation of anisotropic turbulence." Journal of Fluid Mechanics 582 (June 14, 2007): 377–97. http://dx.doi.org/10.1017/s002211200700599x.

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A new subgrid eddy-viscosity model is proposed in this paper. Full details of the derivation of the model are given with the assumption of homogeneous turbulence. The formulation of the model is based on the dynamic equation of the structure function of resolved scale turbulence. By means of the local volume average, the effect of the anisotropy is taken into account in the generalized Kolmogorov equation, which represents the equilibrium energy transfer in the inertial subrange. Since the proposed model is formulated directly from the filtered Navier–Stokes equation, the resulting subgrid eddy viscosity has the feature that it can be adopted in various turbulent flows without any adjustments of model coefficient. The proposed model predicts the major statistical properties of rotating turbulence perfectly at fairly low-turbulence Rossby numbers whereas subgrid models, which do not consider anisotropic effects in turbulence energy transfer, cannot predict this typical anisotropic turbulence correctly. The model is also tested in plane wall turbulence, i.e. plane Couette flow and channel flow, and the major statistical properties are in better agreement with those predicted by DNS results than the predictions by the Smagorinsky, the dynamic Smagorinsky and the recent Cui–Zhou–Zhang–Shao models.

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Chai, Xiaochuan, and Krishnan Mahesh. "Dynamic -equation model for large-eddy simulation of compressible flows." Journal of Fluid Mechanics 699 (April 16, 2012): 385–413. http://dx.doi.org/10.1017/jfm.2012.115.

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AbstractThis paper presents a dynamic one-equation eddy viscosity model for large-eddy simulation (LES) of compressible flows. The transport equation for subgrid-scale (SGS) kinetic energy is introduced to predict SGS kinetic energy. The exact SGS kinetic energy transport equation for compressible flows is derived formally. Each of the unclosed terms in the SGS kinetic energy equation is modelled separately and dynamically closed, instead of being grouped into production and dissipation terms, as in the Reynolds averaged Navier–Stokes equations. All of the SGS terms in the filtered total energy equation are found to reappear in the SGS kinetic energy equation. Therefore, these terms can be included in the total energy equation without adding extra computational cost. A priori tests using direct numerical simulation (DNS) of decaying isotropic turbulence show that, for a Smagorinsky-type eddy viscosity model, the correlation between the SGS stress and the model is comparable to that from the original model. Also, the suggested model for the pressure dilatation term in the SGS kinetic energy equation is found to have a high correlation with its actual value. In a posteriori tests, the proposed dynamic $k$-equation model is applied to decaying isotropic turbulence and normal shock–isotropic turbulence interaction, and yields good agreement with available experimental and DNS data. Compared with the results of the dynamic Smagorinsky model (DSM), the $k$-equation model predicts better energy spectra at high wavenumbers, similar kinetic energy decay and fluctuations of thermodynamic quantities for decaying isotropic turbulence. For shock–turbulence interaction, the $k$-equation model and the DSM predict similar evolutions of turbulent intensities across shocks, owing to the dominant effect of linear interaction. The proposed $k$-equation model is more robust in that local averaging over neighbouring control volumes is sufficient to regularize the dynamic procedure. The behaviour of pressure dilatation and dilatational dissipation is discussed through the budgets of the SGS kinetic energy equation, and the importance of the dilatational dissipation term is addressed.

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HIRAISHI, Masayuki, and Michihisa TSUTAHARA. "3007 Application of Dynamic Smagorinsky Model to the Finite Difference Lattice Boltzmann Method." Proceedings of The Computational Mechanics Conference 2005.18 (2005): 605–6. http://dx.doi.org/10.1299/jsmecmd.2005.18.605.

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VREMAN, BERT, BERNARD GEURTS, and HANS KUERTEN. "Large-eddy simulation of the turbulent mixing layer." Journal of Fluid Mechanics 339 (May 25, 1997): 357–90. http://dx.doi.org/10.1017/s0022112097005429.

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Six subgrid models for the turbulent stress tensor are tested by conducting large-eddy simulations (LES) of the weakly compressible temporal mixing layer: the Smagorinsky, similarity, gradient, dynamic eddy-viscosity, dynamic mixed and dynamic Clark models. The last three models are variations of the first three models using the dynamic approach. Two sets of simulations are performed in order to assess the quality of the six models. The LES results corresponding to the first set are compared with filtered results obtained from a direct numerical simulation (DNS). It appears that the dynamic models lead to more accurate results than the non-dynamic models tested. An adequate mechanism to dissipate energy from resolved to subgrid scales is essential. The dynamic models have this property, but the Smagorinsky model is too dissipative during transition, whereas the similarity and gradient models are not sufficiently dissipative for the smallest resolved scales. In this set of simulations, at moderate Reynolds number, the dynamic mixed and Clark models are found to be slightly more accurate than the dynamic eddy-viscosity model. The second set of LES concerns the mixing layer at a considerably higher Reynolds number and in a larger computational domain. An accurate DNS for this mixing layer can currently not be performed, thus in this case the LES are tested by investigating whether they resemble a self-similar turbulent flow. It is found that the dynamic models generate better results than the non-dynamic models. The closest approximation to a self-similar state was obtained using the dynamic eddy-viscosity model.

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Kazemi, Ehsan, and Stefan Heinz. "Dynamic Large Eddy Simulations of the Ekman Layer Based on Stochastic Analysis." International Journal of Nonlinear Sciences and Numerical Simulation 17, no. 2 (April 1, 2016): 77–98. http://dx.doi.org/10.1515/ijnsns-2015-0049.

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AbstractLarge eddy simulation (LES) of the neutrally stratified turbulent Ekman layer is performed. In particular, we compare three LES models with direct numerical simulation (DNS), which was validated against existing DNS. The models considered are a standard nondynamic LES model, the Smagorinsky model (SM), a standard dynamic LES model, the stabilized dynamic Smagorinsky model (DSM), and a new linear dynamic model (LDM), which was derived from a realizable stochastic turbulence model. The following conclusions are obtained. The SM does not represent an appropriate model for the flow considered. Mean velocity and turbulence intensities are poorly predicted. With respect to instantaneous fields, the SM provides a tilting of turbulence structures in the opposite direction as seen in DNS. The stabilized DSM also suffers from significant shortcomings. First, its behavior depends on the wall distance. Close to the wall, it produces acceptable turbulence structures. Away from the wall, it suffers from the same shortcomings as the SM. Second, it incorrectly describes the effect of grid coarsening. The new LDM is free from the disadvantages of the SM and stabilized DSM. Its predictions of both mean and instantaneous velocity fields agree very well with DNS. The relevant conclusion is the following. The use of a dynamic LES method represents a mean for correctly simulating large-scale structures (means and stresses), but it does not ensure a correct simultaneous simulation of small-scale structures. Our results indicate that a dynamic method designed in consistency with a realizable stress model can correctly simulate both large-scale and small-scale structures.

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Meneveau, Charles, Thomas S. Lund, and William H. Cabot. "A Lagrangian dynamic subgrid-scale model of turbulence." Journal of Fluid Mechanics 319, no. -1 (July 1996): 353. http://dx.doi.org/10.1017/s0022112096007379.

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Gadalla, Mahmoud, Jeevananthan Kannan, Bulut Tekgül, Shervin Karimkashi, Ossi Kaario, and Ville Vuorinen. "Large-Eddy Simulation of ECN Spray A: Sensitivity Study on Modeling Assumptions." Energies 13, no. 13 (July 1, 2020): 3360. http://dx.doi.org/10.3390/en13133360.

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In this study, various mixing and evaporation modeling assumptions typically considered for large-eddy simulation (LES) of the well-established Engine Combustion Network (ECN) Spray A are explored. A coupling between LES and Lagrangian particle tracking (LPT) is employed to simulate liquid n-dodecane spray injection into hot inert gaseous environment, wherein Lagrangian droplets are introduced from a small cylindrical injection volume while larger length scales within the nozzle diameter are resolved. This LES/LPT approach involves various modeling assumptions concerning the unresolved near-nozzle region, droplet breakup, and LES subgrid scales (SGS) in which their impact on common spray metrics is usually left unexplored despite frequent utilization. Here, multi-parametric analysis is performed on the effects of (i) cylindrical injection volume dimensions, (ii) secondary breakup model, particularly Kelvin–Helmholtz Rayleigh–Taylor (KHRT) against a no-breakup model approach, and (iii) LES SGS models, particularly Smagorinsky and one-equation models against implicit LES. The analysis indicates the following findings: (i) global spray characteristics are sensitive to radial dimension of the cylindrical injection volume, (ii) the no-breakup model approach performs equally well, in terms of spray penetration and mixture formation, compared with KHRT, and (iii) the no-breakup model is generally insensitive to the chosen SGS model for the utilized grid resolution.

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Yang, Chenghao, Heying Feng, and Yehui Peng. "Noise characteristic analysis and sound sources identification for rod–airfoil interaction using different subgrid-scale models." E3S Web of Conferences 233 (2021): 04036. http://dx.doi.org/10.1051/e3sconf/202123304036.

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Four subgrid-scale models based on large eddy simulation (LES), such as Smagorinsky–Lilly (SL), dynamic Smagorinsky–Lilly (DSL), wall-adapting local eddy-viscosity (WALE), and dynamic kinetic-energy transport (KET) were used and couple Ffowcs Williams–Hawkings equation to accurately analyze and identify the characteristics and position of the sound sources of rod–airfoil interaction. The results of four models were compared with experimental data. It was found that the DSL model was the optimal subgrid-scale model for the study of the interaction noise considering the calculation accuracy. Therefore, the DSL model was selected for analyzing and identifying the characteristics and location of the interaction noise source. During the calculation, solid and permeable data surfaces were used for acoustic integral surfaces. The results show that the impact of the quadrupole source is negligible at a low Mach number, and the dipole noise coming from the pressure fluctuations is dominant. Meanwhile, the dipole noise from the airfoil is louder than that from the rod; the leading edge of about 30% chord length of airfoil the is the main sound source of interference effect. Above results can provide guidance for research of blade-vortex interaction noise.

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Schaefer-Rolffs, Urs, and Erich Becker. "Scale-Invariant Formulation of Momentum Diffusion for High-Resolution Atmospheric Circulation Models." Monthly Weather Review 146, no. 4 (April 2018): 1045–62. http://dx.doi.org/10.1175/mwr-d-17-0216.1.

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A new version of the dynamic Smagorinsky model is presented that applies for nonisotropic momentum diffusion in high-resolution atmospheric circulation models. While the horizontal mixing length is computed in accordance with scale invariance in the mesoscale regime of the horizontal energy cascade, the associated dynamic vertical mixing length (DVML) is based on a recently developed scale invariance criterion and represents an application of the scaling laws of stratified macroturbulence. The DVML is validated in high-resolution simulations with the Kühlungsborn mechanistic general circulation model, using triangular spectral truncation at wavenumber 330 and a vertical level spacing of about 200 m in the upper troposphere. For a proper choice of the test filter, the model simulates a realistic horizontal kinetic energy spectrum in the troposphere along with a realistic intensity of the Lorenz energy cycle. This result is obtained without any hyperdiffusion, and it depends only little on whether the vertical mixing length is prescribed or set to the DVML. The globally averaged Smagorinsky parameter is about c S ≅ 0.53. The latitude–height cross sections show that c S maximizes in regions of strong mesoscale kinetic energy.

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42

Hasslberger, J., L. Engelmann, A. Kempf, and M. Klein. "Robust dynamic adaptation of the Smagorinsky model based on a sub-grid activity sensor." Physics of Fluids 33, no. 1 (January 1, 2021): 015117. http://dx.doi.org/10.1063/5.0032117.

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Meneveau, Charles, and Thomas S. Lund. "The dynamic Smagorinsky model and scale-dependent coefficients in the viscous range of turbulence." Physics of Fluids 9, no. 12 (December 1997): 3932–34. http://dx.doi.org/10.1063/1.869493.

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Vongvit, Rattawut, and Hai Tao Zhu. "Dynamic Model of the 6-DOF Parallel Manipulator Control Using Lagrangian Equation." Applied Mechanics and Materials 157-158 (February 2012): 437–40. http://dx.doi.org/10.4028/www.scientific.net/amm.157-158.437.

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This paper presents the control of the 6-DOF parallel manipulator using Lagrangian equation. The 6-DOF parallel manipulator are composed of fix base and moveable platform are couple by the actuators. The dynamic equations express by Lagrangian equation, the structure of the 6-DOF parallel manipulator and kinematics and are explains in this paper. The 6-DOF parallel manipulator using Lagrangian equation are accurate and good ability.

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Huang, Xianbei, Zhuqing Liu, and Wei Yang. "Comparative study of SGS models for simulating the flow in a centrifugal-pump impeller using single passage." Engineering Computations 32, no. 7 (October 5, 2015): 2120–35. http://dx.doi.org/10.1108/ec-09-2014-0193.

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Purpose – The purpose of this paper is to bring in and clarify the performance of the Vreman and dynamic Vreman models (VM and DVM) in simulating the internal flow of the centrifugal pump impeller. Design/methodology/approach – Four subgrid scale (SGS) models, including the Smagorinsky model, the dynamic Smagorinsky model, the VM and the DVM are chosen to study the performance in predicting the flow field in the centrifugal pump impeller at design load. The velocity and turbulent kinetic energy distributions are compared. Also, the temporal variation of the model coefficient of the DVM is studied. Findings – The results of all the four models show agreement with both the PIV and LDV data. It is clarified that the VM and the DVM are adaptive in simulating the turbulent flow in the centrifugal pump at design load, and the DVM shows even better performance in predicting the velocity distribution. Additionally, the temporal variation of the model coefficient of the DVM is about 0.01, which is the optimal value for VM in this study. It is verified that VM can perform as good as the dynamic models when an appropriate model coefficient is chosen. Originality/value – The applicability of the VM and the DVM in simulating the internal flow of the centrifugal pump has been proven at design load. The introducing of the two models into centrifugal pump’s simulation can provide some new ideas in constructing more adaptive SGS models for this kind of high-rotating flow.

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Kirkpatrick, M. P., A. S. Ackerman, D. E. Stevens, and N. N. Mansour. "On the Application of the Dynamic Smagorinsky Model to Large-Eddy Simulations of the Cloud-Topped Atmospheric Boundary Layer." Journal of the Atmospheric Sciences 63, no. 2 (February 1, 2006): 526–46. http://dx.doi.org/10.1175/jas3651.1.

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Abstract In this paper the dynamic Smagorinsky model originally developed for engineering flows is adapted for simulations of the cloud-topped atmospheric boundary layer in which an anelastic form of the governing equations is used. The adapted model accounts for local buoyancy sources, vertical density stratification, and poor resolution close to the surface and calculates additional model coefficients for the subgrid-scale fluxes of potential temperature and total water mixing ratio. Results obtained with the dynamic model are compared with those obtained using two nondynamic models for simulations of a nocturnal marine stratocumulus cloud deck observed during the first research flight of the second Dynamics and Chemistry of Marine Stratocumulus (DYCOMS-II) field experiment. The dynamic Smagorinsky model is found to give better agreement with the observations for all parameters and statistics. The dynamic model also gives improved spatial convergence and resolution independence over the nondynamic models. The good results obtained with the dynamic model appear to be due primarily to the fact that it calculates minimal subgrid-scale fluxes at the inversion. Based on other results in the literature, it is suggested that entrainment in the DYCOMS-II case is due predominantly to isolated mixing events associated with overturning internal waves. While the behavior of the dynamic model is consistent with this entrainment mechanism, a similar tendency to switch off subgrid-scale fluxes at an interface is also observed in a case in which gradient transport by small-scale eddies has been found to be important. This indicates that there may be problems associated with the application of the dynamic model close to flow interfaces. One issue here involves the plane-averaging procedure used to stabilize the model, which is not justified when the averaging plane intersects a deforming interface. More fundamental, however, is that the behavior may be due to insufficient resolution in this region of the flow. The implications of this are discussed with reference to both dynamic and nondynamic subgrid-scale models, and a new approach to turbulence modeling for large-eddy simulations is proposed.

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Basu, Sukanta, Jean-François Vinuesa, and Andrew Swift. "Dynamic LES Modeling of a Diurnal Cycle." Journal of Applied Meteorology and Climatology 47, no. 4 (April 1, 2008): 1156–74. http://dx.doi.org/10.1175/2007jamc1677.1.

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Abstract The diurnally varying atmospheric boundary layer observed during the Wangara (Australia) case study is simulated using the recently proposed locally averaged scale-dependent dynamic subgrid-scale (SGS) model. This tuning-free SGS model enables one to dynamically compute the Smagorinsky coefficient and the subgrid-scale Prandtl number based on the local dynamics of the resolved velocity and temperature fields. It is shown that this SGS-model-based large-eddy simulation (LES) has the ability to faithfully reproduce the characteristics of observed atmospheric boundary layers even with relatively coarse resolutions. In particular, the development, magnitude, and location of an observed nocturnal low-level jet are depicted quite well. Some well-established empirical formulations (e.g., mixed layer scaling, spectral scaling) are recovered with good accuracy by this SGS parameterization. The application of this new-generation dynamic SGS modeling approach is also briefly delineated to address several practical wind-energy-related issues.

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Enayati, Hooman, and Minel J. Braun. "2D/3D RANS and LES Calculations of Natural Convection in a Laterally-Heated Cylindrical Enclosure Using Boussinesq and Temperature-Dependent Formulations." International Journal of Heat and Technology 39, no. 6 (December 31, 2021): 1979–90. http://dx.doi.org/10.18280/ijht.390637.

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This article presents an investigation of fluid flow and natural convection heat transfer in a cylindrical enclosure heated laterally. Two-dimensional (2D) Reynolds-averaged Navier–Stokes (RANS) equations and three-dimensional (3D) Large Eddy Simulation (LES) calculations are conducted using commercial computational fluid dynamics (CFD) software, ANSYS FLUENT. The Rayleigh number (Ra) = 2E+7 is constant in all of the simulations and is based on a length scale that is equal to the ratio of volume to the lateral area of the reactor, i.e., R/2, where R is the radius of the reactor. The validity of the Boussinesq approximation is analyzed by comparing calculations using both the Boussinesq approximation and temperature-dependent properties (non-Boussinesq approach) using 2D RANS and 3D LES (Dynamic Smagorinsky) formulations. Moreover, 2D axisymmetric k-ω SST RANS model will be implemented to investigate whether the 2D axisymmetric model can give results that are comparable to those of the 3D LES (Dynamic Smagorinsky) model when the corresponding longitudinal or azimuthal cross section are compared. In other words, the validity of using a 2D model instead of a 3D model for the current geometry, flow regime and thermal boundary conditions will be discussed. The flow and temperature contours of these two types of simulations are analyzed, compared to determine the various aspects of each case and discussed for deeper physical insight.

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Pesmazoglou, I., A. M. Kempf, and S. Navarro-Martinez. "A dynamic model for the Lagrangian stochastic dispersion coefficient." Physics of Fluids 25, no. 12 (December 2013): 125108. http://dx.doi.org/10.1063/1.4848855.

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Blishchik, A., and S. Kenjereš. "Dynamic LES of the magnetohydrodynamic flow in a square duct with the varied wall conductance parameters." Journal of Physics: Conference Series 2116, no. 1 (November 1, 2021): 012036. http://dx.doi.org/10.1088/1742-6596/2116/1/012036.

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Abstract The current study is focused on the magnetohydrodynamics and demonstrates how electrical conductivity of the wall can affect the turbulent flow in the square duct. Different variations of the boundary walls have been considered including arbitrary conductive walls. The Large Eddy Simulations method with the dynamic Smagorinsky sub-grid scale model have been used for the turbulent structures resolving. Results show the significant impact of the wall conductance parameters for both Hartmann and side walls.

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Journal articles on the topic 'Lagrangian Dynamic Smagorinsky model'

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