Download or read book Turbulence Kinetic Energy Budgets and Dissipation Rates in Disturbed Stable Boundary Layers written by J. K. Lundquist and published by . This book was released on 2004 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important parameter in the numerical simulation of atmospheric boundary layers is the dissipation length scale, l{sub {var_epsilon}}. It is especially important in weakly to moderately stable conditions, in which a tenuous balance between shear production of turbulence, buoyant destruction of turbulence, and turbulent dissipation is maintained. In large-scale models, the dissipation rate is often parameterized using a diagnostic equation based on the production of turbulent kinetic energy (TKE) and an estimate of the dissipation length scale. Proper parameterization of the dissipation length scale from experimental data requires accurate estimation of the rate of dissipation of TKE from experimental data. Using data from the MICROFRONTS and CASES-99 field programs, we evaluate turbulent kinetic energy (TKE), TKE dissipation rate {var_epsilon}, and dissipation length l{sub {var_epsilon}} over a range of stability regimes represented by a stable boundary layer (SBL), a destabilizing intrusion (by first a cold front and second a density current) and recovery. These data may be utilized to test recent parameterizations of dissipation rate {var_epsilon} and l{sub {var_epsilon}} in order to determine the suitability of these models for inclusion in mesoscale models for numerical weather prediction or pollution dispersion prediction.
Download or read book Modeling Disturbance Dynamics in Transitional and Turbulent Boundary Layers written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-20 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamics of an ensemble of linear disturbances in boundary-layer flows at various Reynolds numbers is studied through an analysis of the transport equations for the mean disturbance kinetic energy and energy dissipation rate. Effects of adverse and favorable pressure-gradients on the disturbance dynamics are also included in the analysis. Unlike the fully turbulent regime where nonlinear phase scrambling of the fluctuations affects the flow field even in proximity to the wall, the early stage transition regime fluctuations studied here are influenced across the boundary layer by the solid boundary. In addition, the dominating dynamics in the disturbance kinetic energy equation is governed by the energy production, pressure-transport and viscous diffusion - also in contrast to the fully turbulent regime. For the disturbance dissipation rate, a dynamic balance exists between the destruction and diffusion of dissipation.Grosch, C. E. and Gatski, T. B. (Technical Monitor)Langley Research CenterPRESSURE GRADIENTS; REYNOLDS NUMBER; TURBULENT BOUNDARY LAYER; BOUNDARY LAYER FLOW; FLOW DISTRIBUTION; COMPUTERIZED SIMULATION; WALL FLOW; ENERGY BUDGETS; ENERGY DISSIPATION
Download or read book Statistical Characteristics of Turbulence and the Budget of Turbulent Energy in the Surface Boundary Layer written by Kenji Kai and published by . This book was released on 1982 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Developments in the Computation of Turbulent Boundary Layers written by Morris W. Rubesin and published by . This book was released on 1979 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Atmospheric Boundary Layer written by J. R. Garratt and published by Cambridge University Press. This book was released on 1994-04-21 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book gives a comprehensive and lucid account of the science of the atmospheric boundary layer (ABL). There is an emphasis on the application of the ABL to numerical modelling of the climate. The book comprises nine chapters, several appendices (data tables, information sources, physical constants) and an extensive reference list. Chapter 1 serves as an introduction, with chapters 2 and 3 dealing with the development of mean and turbulence equations, and the many scaling laws and theories that are the cornerstone of any serious ABL treatment. Modelling of the ABL is crucially dependent for its realism on the surface boundary conditions, and chapters 4 and 5 deal with aerodynamic and energy considerations, with attention to both dry and wet land surfaces and sea. The structure of the clear-sky, thermally stratified ABL is treated in chapter 6, including the convective and stable cases over homogeneous land, the marine ABL and the internal boundary layer at the coastline. Chapter 7 then extends the discussion to the cloudy ABL. This is seen as particularly relevant, since the extensive stratocumulus regions over the subtropical oceans and stratus regions over the Arctic are now identified as key players in the climate system. Finally, chapters 8 and 9 bring much of the book's material together in a discussion of appropriate ABL and surface parameterization schemes in general circulation models of the atmosphere that are being used for climate simulation.
Download or read book Turbulent Boundary Layers written by Helmut E. Weber and published by . This book was released on 1979 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Turbulent Kinetic Energy in Boundary Layers and Grid Turbulence written by Robert James Smalley and published by . This book was released on 2002 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Vorticity Dynamics Based Model for the Turbulent Dissipation written by Tsan-Hsing Shih and published by . This book was released on 1994 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Turbulent Boundary Layers written by Tuncer Cebeci and published by Elsevier. This book was released on 2012-12-02 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculating two-dimensional and axisymmetric laminar and turbulent boundary layers. This book will be useful to readers who have advanced knowledge in fluid mechanics, especially to engineers who study the important problems of design.
Download or read book Progress in Turbulence Modeling for Complex Flow Fields Including Effects of Compressibility written by David C. Wilcox and published by . This book was released on 1980 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Calculations of Oblique Shock Wave turbulent Boundary layer Interactions with New Two equation Turbulence Models written by William W.-W. Liou and published by . This book was released on 1996 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Structure of Atmospheric Turbulence written by John Leask Lumley and published by . This book was released on 1964 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Galilean and Tensorial Invariant K e Model for Near Wall Turbulence written by Z. Yang and published by . This book was released on 1993 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Contribution to the Calculation of Turbulent Boundary Layers written by Julius C. Rotta and published by . This book was released on 1951 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Critical Evaluation of Two Equation Models for Near Wall Turbulence written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-27 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: A variety of two-equation turbulence models, including several versions of the K-epsilon model as well as the K-omega model, are analyzed critically for near wall turbulent flows from a theoretical and computational standpoint. It is shown that the K-epsilon model has two major problems associated with it: the lack of natural boundary conditions for the dissipation rate and the appearance of higher-order correlations in the balance of terms for the dissipation rate at the wall. In so far as the former problem is concerned, either physically inconsistent boundary conditions have been used or the boundary conditions for the dissipation rate have been tied to higher-order derivatives of the turbulent kinetic energy which leads to numerical stiffness. The K-omega model can alleviate these problems since the asymptotic behavior of omega is known in more detail and since its near wall balance involves only exact viscous terms. However, the modeled form of the omega equation that is used in the literature is incomplete-an exact viscous term is missing which causes the model to behave in an asymptotically inconsistent manner. By including this viscous term and by introducing new wall damping functions with improved asymptotic behavior, a new K-tau model (where tau is identical with 1/omega is turbulent time scale) is developed. It is demonstrated that this new model is computationally robust and yields improved predictions for turbulent boundary layers. Speziale, Charles G. and Abid, Ridha and Anderson, E. Clay Langley Research Center NAS1-18605..
Download or read book The Use of Turbulence Energy Equation in Boundary Layer Study written by Ro-Chi Tai and published by . This book was released on 1969 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: "A turbulent boundary layer problem has been studied analytically and compared with an available experiment in the literature. Correlations of the experimental data were made to investigate the validity of the commonly used empirical relations on turbulent shear stresses. It was found that the model which related the local turbulent shear stress linearly with the local turbulent kinetic energy, as used by Bradshow et. al., appeared to be most reasonable. combining this model with the expression of turbulent viscosity given by Boussinesq, it was then possible to introduce the turbulence-energy equation in addition to the governing equations of continuity and momentum. consequently, the turbulent viscosity was able to be considered as one of the dependent variables to be solved for simultaneously with all other related flow parameters. Using the main-flow direction and the stream function as the two independent variables, the governing equations were reduced to two simultaneous parabolic-type partial differential equations through the von Mises transformation. The finite difference technique of Partankar was applied. The numerical solutions were obtained for the average velocity and the turbulent kinetic energy distributions. In comparison with the experimental results of Klebanoff in the fully developed region along a flat plate, very good agreement was reached on average velocity distribution. However, the turbulent kinetic energy distribution was not completely satisfactory, since the energy dissipation term of the turbulence-energy equation was not able to be expressed adequately due to the lack of sufficient experimental information. It is then concluded that the use of the turbulence-energy equation in boundary layer study is possible to eliminate the uncertainty resulting with empirical models of the turbulent viscosity. However, further experimental investigations are needed to improve the understanding of the structure of turbulence"--Abstract, leaves i-ii.
Download or read book The Effect of Stable Stratification on Decaying Grid generated Turbulence written by Kyunghwan Yoon and published by . This book was released on 1989 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt:
