Second Order Closure Modeling Of Variable Density Turbulent Flows
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Author | : Ashok Kumara Varmer |
Publisher | : |
Total Pages | : 37 |
Release | : 1979 |
Genre | : Combustion gases |
ISBN | : |
Mixing and Chemical reactions under turbulent flow conditions are a basic feature of the energy release processes in many combustion and propulsion systems. The development of predictive calculation procedures for these systems requires the understanding and modeling of coupling between turbulence and various physical and chemical processes. Second-order closure modeling of turbulent flows provides a rational framework for studying these interactions. Models for the scalar probability density function (pdf) have to be developed to achieve closure of turbulent transport equations for mixing and reacting flows. A delta function 'typical eddy' pdf model for two species flows has been developed and incorporated into a complete second-order closure computer program. The program has been used to study uniform and variable density flowfields and the model predictions have been compared to experimental measurements. The modeling of turbulence dynamics for variable density flows requires further improvement. However, the importance of modeling the higher-order scalar correlations has been demonstrated. A number of statistical constraints on three species flowfields have also been derived. These will be useful in the development of the 'typical eddy' pdf modelfor reacting flows. (Author).
Author | : P. Chassaing |
Publisher | : Springer Science & Business Media |
Total Pages | : 387 |
Release | : 2013-06-29 |
Genre | : Science |
ISBN | : 9401700753 |
The first part aims at providing the physical and theoretical framework of the analysis of density variations in fully turbulent flows. Its scope is deliberately educational. In the second part, basic data on dynamical and scalar properties of variable density turbulent flows are presented and discussed, based on experimental data and/or results from direct numerical simulations. This part is rather concerned with a research audience. The last part is more directly devoted to an engineering audience and deals with prediction methods for turbulent flows of variable density fluid. Both first and second order, single point modeling are discussed, with special emphasis on the capability to include specific variable density / compressibility effects.
Author | : Mohammad Farshchi |
Publisher | : |
Total Pages | : 340 |
Release | : 1985 |
Genre | : |
ISBN | : |
Author | : Charles G. Speziale |
Publisher | : |
Total Pages | : 32 |
Release | : 1991 |
Genre | : Shear flow |
ISBN | : |
Author | : Ashok Kumara Varma |
Publisher | : |
Total Pages | : 54 |
Release | : 1978 |
Genre | : Combustion |
ISBN | : |
Turbulent flows involving chemical reactions are a basic feature of many combustion and propulsion systems. The development of calculation procedures for turbulent reacting flows requires the understanding and modeling of the coupling between turbulence and combustion. Second-order closure modeling of turbulent flows provides a convenient framework for studying these interactions between turbulence and chemical reactions. Models for the scalar probability density function (pdf) have to be developed to achieve closure of turbulent transport equations for mixing and reacting flows. A delta function 'typical eddy' model has been developed for the joint pdf of the scalar variables. It has been demonstrated that delta functions are a necessary part of pdf's in order to attain the extremums of the statistical constraints on the moments. The statistical bounds on a number of moments of interest have been derived. It has been proven that a rational pdf composed of a set of delta functions alone can always be constructed at any point within the statistically valid moment space. The model provides a good representation of actual pdf's in two-species, variable-density mixing flows. The model has been directly compared to experimental pdf measurements and good agreement for higher-order moments has been demonstrated. It can be shown that the delta function pdf model is significantly simpler than other proposed pdf models and is more than adequate for the closure of the transport equations. (Author).
Author | : Tsan-Hsing Shih |
Publisher | : |
Total Pages | : 266 |
Release | : 1984 |
Genre | : Fluid dynamics |
ISBN | : |
Author | : Ching Jen Chen |
Publisher | : CRC Press |
Total Pages | : 312 |
Release | : 1997-12-01 |
Genre | : Technology & Engineering |
ISBN | : 9781560324058 |
Focuses on the second-order turbulence-closure model and its applications to engineering problems. Topics include turbulent motion and the averaging process, near-wall turbulence, applications of turbulence models, and turbulent buoyant flows.
Author | : Charles G. Speziale |
Publisher | : |
Total Pages | : 32 |
Release | : 1985 |
Genre | : |
ISBN | : |
Author | : Jordan M. MacInnes |
Publisher | : |
Total Pages | : 220 |
Release | : 1980 |
Genre | : |
ISBN | : |
Author | : National Aeronautics and Space Adm Nasa |
Publisher | : |
Total Pages | : 70 |
Release | : 2018-11-03 |
Genre | : |
ISBN | : 9781730800474 |
A second order closure turbulence model for compressible flows is developed and implemented in a 2D Reynolds-averaged Navier-Stokes solver. From the beginning where a kappa-epsilon turbulence model was implemented in the bidiagonal implicit method of MACCORMACK (referred to as the MAC3 code) to the final stage of implementing a full second order closure in the efficient line Gauss-Seidel algorithm, numerous work was done, individually and collectively. Besides the collaboration itself, the final product of this work is a second order closure derived from the Launder, Reece, and Rodi model to account for near wall effects, which has been called FRAME model, which stands for FRench-AMerican-Effort. During the reporting period, two different problems were worked out. The first was to provide Ames researchers with a reliable compressible boundary layer code including a wide collection of turbulence models for quick testing of new terms, both in two equations and in second order closure (LRR and FRAME). The second topic was to complete the implementation of the FRAME model in the MAC5 code. The work related to these two different contributions is reported. dilatation in presence of stron shocks. This work, which has been conducted during a work at the Center for Turbulence Research with Zeman aimed also to cros-check earlier assumptions by Rubesin and Vandromme. Haminh, Hieu and Kollmann, Wolfgang and Vandromme, Dany Unspecified Center...