Journal ArticleDOI
On nonlinear K-l and K-ε models of turbulence
Reads0
Chats0
TLDR
In this paper, a nonlinear K-l and K-e model is proposed to predict the normal Reynolds stresses in turbulent channel flow much more accurately than the linear model, and the nonlinear model is shown to be capable of predicting turbulent secondary flows in non-circular ducts.Abstract:
The commonly used linear K-l and K-e models of turbulence are shown to be incapable of accurately predicting turbulent flows where the normal Reynolds stresses play an important role. By means of an asymptotic expansion, nonlinear K-l and K-e models are obtained which, unlike all such previous nonlinear models, satisfy both realizability and the necessary invariance requirements. Calculations are presented which demonstrate that this nonlinear model is able to predict the normal Reynolds stresses in turbulent channel flow much more accurately than the linear model. Furthermore, the nonlinear model is shown to be capable of predicting turbulent secondary flows in non-circular ducts - a phenomenon which the linear models are fundamentally unable to describe. An additional application of this model to the improved prediction of separated flows is discussed briefly along with other possible avenues of future research.read more
Citations
More filters
CFD-Simulationen turbulenter konvektiver Strömungen bei überkritischen Drücken
TL;DR: Fluide bei Drucken um den thermodynamisch kritischen Punkt unterliegen starken Anderungen der Stoffeigenschaften Diese interagieren with der Turbulenzproduktion in direkter Wandnahe, was lokal zu einer Verschlechterung des Warmeubergangs fuhren kann as mentioned in this paper.
Journal ArticleDOI
Localized air-conditioning with upper-room UVGI to reduce airborne bacteria cross-infection
TL;DR: In this paper, the authors investigated the effectiveness of upper-room ultraviolet germicidal irradiation (UVGI) in reducing airborne bacteria transmission within a zone conditioned by localized ceiling-mounted airconditioning system that recirculates return air.
Journal ArticleDOI
A K–L model with improved realizability for turbulent mixing
TL;DR: In this article, a realizable K-L mixing model is developed, extended from the standard k-L model given by Shih et al. to reproduce the growth rate of the Kelvin-Helmholtz mixing.
Journal ArticleDOI
Pressure Drop and Energy Recovery with a New Centrifugal Micro-Turbine: Fundamentals and Application in a Real WDN
Maria Cristina Morani,Mariana Simão,Ignac Gazur,R.S. Santos,Armando Carravetta,Oreste Fecarotta,Helena M. Ramos +6 more
TL;DR: In this article , computational fluid dynamics (CFD) modeling is coupled with experimental tests in order to investigate the optimal performance of a new centrifugal turbine, where the behavior of the flow through the turbine runner is assessed by means of velocity profiles and pressure contours at all components of the machine under different operating conditions.
Journal ArticleDOI
Reynolds stress model involving the mean spin tensor.
Yu-Ning Huang,Hui-Yang Ma +1 more
TL;DR: Numerical results based on this model, in the forms of employing the Jaumann derivative and the Oldroyd derivative, for homogeneous turbulent shear flow and fully developed turbulent flow over a backward-facing step, are presented, showing reasonably good agreement with the experimental results and the DNS data concerned and a better performance than the previously developed quadratic models.
References
More filters
Journal ArticleDOI
Progress in the development of a Reynolds-stress turbulence closure
TL;DR: In this article, the authors developed a model of turbulence in which the Reynolds stresses are determined from the solution of transport equations for these variables and for the turbulence energy dissipation rate E. Particular attention is given to the approximation of the pressure-strain correlations; the forms adopted appear to give reasonably satisfactory partitioning of the stresses both near walls and in free shear flows.
Journal ArticleDOI
A numerical study of three-dimensional turbulent channel flow at large Reynolds numbers
TL;DR: In this article, the three-dimensional, primitive equations of motion have been integrated numerically in time for the case of turbulent, plane Poiseuille flow at very large Reynolds numbers.
Journal ArticleDOI
Numerical investigation of turbulent channel flow
Parviz Moin,John Kim +1 more
TL;DR: In this article, a large-scale flow field was obtained by directly integrating the filtered, three-dimensional, time dependent, Navier-Stokes equations, and small-scale field motions were simulated through an eddy viscosity model.
Book ChapterDOI
Computational Modeling of Turbulent Flows
TL;DR: In this article, it is shown that direct simulation is not an alternative for practical computation and that the various sophisticated closures suffer from essentially the same problems as the direct simulations and therefore, are limited to homogeneous situations.
Journal ArticleDOI
A Reynolds stress model of turbulence and its application to thin shear flows
Kemal Hanjalic,Brian Launder +1 more
TL;DR: In this paper, the authors provided a model of turbulence which effects closure through approximated transport equations for the Reynolds stress tensor the turbulence energy κ and e.g., the turbulent shear stress does not vanish where the mean rate of strain goes to zero.