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Center for Turbulence Research

About: Center for Turbulence Research is a based out in . It is known for research contribution in the topics: Turbulence & Large eddy simulation. The organization has 288 authors who have published 592 publications receiving 53058 citations.

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Journal ArticleDOI
TL;DR: In this article, the authors 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.

5,832 citations

Journal ArticleDOI
TL;DR: In this article, a boundary condition formulation for the Navier-Stokes equations is proposed, which is compatible with non-disjoint algorithms applicable to direct simulations of turbulent flows.

3,214 citations

Journal ArticleDOI
TL;DR: In this article, a method for generating three-dimensional, time-dependent turbulent inflow data for simulations of complex spatially developing boundary layers is described, which is essentially a variant of the Spalart method, optimized so that an existing inflow?outflow code can be converted to an inflow-generation device through the addition of one simple subroutine.

1,462 citations

Journal ArticleDOI
TL;DR: In this paper, the Smagorinsky eddy-viscosity model is combined with a spatially averaged dynamic model for complex-geometry inhomogeneous flows, and a new dynamic model formulation is introduced that combines advantages of the statistical and local approaches.
Abstract: The dynamic model for large-eddy simulation of turbulence samples information from the resolved velocity field in order to optimize subgrid-scale model coefficients. When the method is used in conjunction with the Smagorinsky eddy-viscosity model, and the sampling process is formulated in a spatially local fashion, the resulting coefficient field is highly variable and contains a significant fraction of negative values. Negative eddy viscosity leads to computational instability and as a result the model is always augmented with a stabilization mechanism. In most applications the model is stabilized by averaging the relevant equations over directions of statistical homogeneity. While this approach is effective, and is consistent with the statistical basis underlying the eddy-viscosity model, it is not applicable to complex-geometry inhomogeneous flows. Existing local formulations, intended for inhomogeneous flows, are most commonly stabilized by artificially constraining the coefficient to be positive. In this paper we introduce a new dynamic model formulation, that combines advantages of the statistical and local approaches. We propose to accumulate the required averages over flow pathlines rather than over directions of statistical homogeneity. This procedure allows the application of the dynamic model with averaging to in-homogeneous flows in complex geometries. We analyse direct numerical simulation data to document the effects of such averaging on the Smagorinsky coefficient. The characteristic Lagrangian time scale over which the averaging is performed is chosen based on measurements of the relevant Lagrangian autocorrelation functions, and on the requirement that the model be purely dissipative, guaranteeing numerical stability when coupled with the Smagorinsky model. The formulation is tested in forced and decaying isotropic turbulence and in fully developed and transitional channel flow. In homogeneous flows, the results are similar to those of the volume-averaged dynamic model, while in channel flow, the predictions are slightly superior to those of the spatially (planar) averaged dynamic model. The relationship between the model and vortical structures in isotropic turbulence, as well as ejection events in channel flow, is investigated. Computational overhead is kept small (about 10% above the CPU requirements of the spatially averaged dynamic model) by using an approximate scheme to advance the Lagrangian tracking through first-order Euler time integration and linear interpolation in space.

1,149 citations

Journal ArticleDOI
TL;DR: In this article, a new approach to chemistry modelling for large-eddy simulation of turbulent reacting flows is developed, whereby all of the detailed chemical processes are mapped to a reduced system of tracking scalars.
Abstract: A new approach to chemistry modelling for large-eddy simulation of turbulent reacting flows is developed. Instead of solving transport equations for all of the numerous species in a typical chemical mechanism and modelling the unclosed chemical source terms, the present study adopts an indirect mapping approach, whereby all of the detailed chemical processes are mapped to a reduced system of tracking scalars. Here, only two such scalars are considered: a mixture fraction variable, which tracks the mixing of fuel and oxidizer, and a progress variable, which tracks the global extent of reaction of the local mixture. The mapping functions, which describe all of the detailed chemical processes with respect to the tracking variables, are determined by solving quasi-steady diffusion-reaction equations with complex chemical kinetics and multicomponent mass diffusion. The performance of the new model is compared to fast-chemistry and steady-flamelet models for predicting velocity, species concentration, and temperature fields in a methane-fuelled coaxial jet combustor for which experimental data are available. The progress-variable approach is able to capture the unsteady, lifted flame dynamics observed in the experiment, and to obtain good agreement with the experimental data, while the fast-chemistry and steady-flamelet models both predict an attached flame.

1,102 citations


Showing all 288 results

Parviz Moin11647360521
George Em Karniadakis10478549690
John Kim9040641986
Charles Meneveau7847425607
Thierry Poinsot7228124266
Petros Koumoutsakos7137521325
Heinz Pitsch6949818698
Sanjiva K. Lele6538820964
Rajat Mittal6133417041
Javier Jiménez6127718061
Eric S. G. Shaqfeh5422410213
Nikolaus A. Adams5340811879
David C. Samuels522189545
Juan J. Alonso512909987
Xiaohua Wu482118361
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