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Proceedings ArticleDOI

Numerical method for large eddy simulation of compressible isotropic turbulence

17 Jun 2019-pp 1-12

About: The article was published on 2019-06-17. It has received 2 citation(s) till now. The article focuses on the topic(s): Large eddy simulation & Isotropy.
Topics: Large eddy simulation (67%), Isotropy (53%), Turbulence (52%)
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Journal Article
Abstract: The thermal effects of plasmas on isotropic turbulence are studied using direct numerical simulations. The temperature ratio of the plasma region to the background region is moderate. Two idealizations of the plasma are considered – spherical and conical. The conical idealization is found preferable in that it approximates the tear–drop shape of the plasma region that is observed experimentally, and produces baroclinic vorticity. The variation of the magnitude of the vorticity with temperature ratio and size of plasma region is examined. A blast wave followed by a region of expansion propagates normal to the axis of the plasma region. The turbulence is observed to be suppressed in the core of the plasma, presumably due to bulk expansion.

1 citations

Proceedings ArticleDOI
Shankar Ghosh1, Badal Modi1Institutions (1)
11 Jan 2021

1 citations

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Journal ArticleDOI
Abstract: One 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 coefficient is computed dynamically as the calculation progresses rather than input a priori. The model is based on an algebraic identity between the subgrid‐scale stresses at two different filtered levels and the resolved turbulent stresses. The subgrid‐scale stresses obtained using the proposed model vanish in laminar flow and at a solid boundary, and have the correct asymptotic behavior in the near‐wall region of a turbulent boundary layer. The results of large‐eddy simulations of transitional and turbulent channel flow that use the proposed model are in good agreement with the direct simulation data.

6,329 citations

Journal ArticleDOI
Sanjiva K. Lele1Institutions (1)
Abstract: The present finite-difference schemes for the evaluation of first-order, second-order, and higher-order derivatives yield improved representation of a range of scales and may be used on nonuniform meshes. Various boundary conditions may be invoked, and both accurate interpolation and spectral-like filtering can be accomplished by means of schemes for derivatives at mid-cell locations. This family of schemes reduces to the Pade schemes when the maximal formal accuracy constraint is imposed with a specific computational stencil. Attention is given to illustrative applications of these schemes in fluid dynamics.

5,460 citations

Journal ArticleDOI
Abstract: The dynamic subgrid-scale (SGS) model of Germano et al. (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 Prandtl number was evaluated using direct numerical simulation (DNS) data in isotropic turbulence, homogeneous shear flow, and turbulent channel flow. The qualitative behavior of the model for turbulent Prandtl number and its dependence on molecular Prandtl number, direction of scalar gradient, and distance from the wall are in accordance with the total turbulent Prandtl number from the DNS data.

1,478 citations

Journal ArticleDOI
Abstract: New subgrid-scale models for the large-eddy simulation of compressible turbulent flows are developed and tested based on the Favre-filtered equations of motion for an ideal gas. A compressible generalization of the linear combination of the Smagorinsky model and scale-similarity model, in terms of Favre-filtered fields, is obtained for the subgrid-scale stress tensor. An analogous thermal linear combination model is also developed for the subgrid-scale heat flux vector. The two dimensionless constants associated with these subgrid-scale models are obtained by correlating with the results of direct numerical simulations of compressible isotropic turbulence performed on a 96 (exp 3) grid using Fourier collocation methods. Extensive comparisons between the direct and modeled subgrid-scale fields are provided in order to validate the models. A large-eddy simulation of the decay of compressible isotropic turbulence (conducted on a coarse 32(exp 3) grid) is shown to yield results that are in excellent agreement with the fine-grid direct simulation. Future applications of these compressible subgrid-scale models to the large-eddy simulation of more complex supersonic flows are discussed briefly.

685 citations

01 Jan 2009
Abstract: LES Governing Equations.- Compressible Turbulence Dynamics.- Functional Modeling.- Explicit Structural Modeling.- Relation Between SGS Model and Numerical Discretization.- Boundary Conditions for Large-Eddy Simulation of Compressible Flows.- Subsonic Applications with Compressibility Effects.- Supersonic Applications.- Supersonic Applications with Shock-Turbulence Interaction.

367 citations

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