Download or read book Analysis of Three dimensional Turbulent Wakes by Momentum Integral Technique written by B. Lakshminarayana and published by . This book was released on 1987 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Three dimensional Effects in Viscous Wakes written by Martin H. Steiger and published by . This book was released on 1962 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: The velocity, energy and concentration fields of three-dimensional viscous wakes are examined with the boundary layer approximations and Oseens' linearization of the acceleration terms. Solutions are derived for both incompressible and compressible wakes, without and with axial pressure gradients. In the incompressible cases the governing equations are linear and transform methods yield exact solutions for general types of initial conditions. In the compressible case the energy equation admits a Crocco integral when the Prandtl and Lewis numbers are equal to unity, and a similar integral of the concentration equation is derived for Le/Pr=1 and Wi tends toward 0. However, due to the nonlinearities associated with compressible flows, solutions for the velocity components can only be achieved by approximate methods. Two methods are presented; the first involves an iteration scheme, while the second assumes that the density and viscosity are only a function of the axial coordinate. In both methods transform theory is used and solutions are presented for general types of initial conditions. As an illustration, it is demonstrated that the axial velocity distribution in isobaric wakes whose initial isovels (lines of constant velocity) are of elliptic shape decay to axial symmetry. (Author).

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1974 with total page 592 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analysis and Control of Three dimensional Turbulent Wakes written by Mathieu Grandemange and published by . This book was released on 2013 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study of the turbulent wake past different geometries is performed by increasing the complexity from axisymmetric bodies to road vehicles. Whatever the geometry is, two kinds of coherent wake motions are likely to be observed. First, at timescales of the order of 5D/U, D and U being the characteristic size and velocity of the flow respectively, the wake may generate periodic oscillations. These coherent motions are usually associated with the interaction of two facing shear layers of opposite vorticity. As the corresponding frequencies rely at first order on the distance between the shear layers, two distinct frequencies are reported when the afterbody has a cross-flow aspect ratio different than 1. These unsteady global modes seem to weaken when the Reynolds number and the complexity of the geometry increase. The second type of coherent motions corresponds to the development of stationary cross-flow instabilities. They are linked to the symmetry breaking modes observed in laminar regimes and their domains of appearance are defined from geometry considerations in the cases of parallelepiped bodies in ground proximity. These instabilities are responsible for strong asymmetries in the instantaneous flow and may generate bistable dynamics with a characteristic time scale of the order of 1000D/U. The study of these phenomena, combined with sensitivity analyses to small perturbations, places the diminution of the cross-flow asymmetries of the instantaneous wake as a relevant strategy for drag reduction. In particular, it is found that both local and global pressure gradients on the sides of the body are source of streamwise vortices increasing the drag. Parabolic dependences between the drag and the cross-flow forces are reported suggesting similarities with the mechanisms of induced drag that are well-known in aeronautics. Consequently, as they often generate significant wake asymmetries, the development of the cross-flow instabilities is identified as a drag contributor. On the contrary, the part of the drag related to the periodic global modes seems to be negligible especially for complex geometries at high Reynolds number.

Download or read book Turbulent Flows written by Jean Piquet and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 767 pages. Available in PDF, EPUB and Kindle. Book excerpt: obtained are still severely limited to low Reynolds numbers (about only one decade better than direct numerical simulations), and the interpretation of such calculations for complex, curved geometries is still unclear. It is evident that a lot of work (and a very significant increase in available computing power) is required before such methods can be adopted in daily's engineering practice. I hope to l"Cport on all these topics in a near future. The book is divided into six chapters, each· chapter in subchapters, sections and subsections. The first part is introduced by Chapter 1 which summarizes the equations of fluid mechanies, it is developed in C~apters 2 to 4 devoted to the construction of turbulence models. What has been called "engineering methods" is considered in Chapter 2 where the Reynolds averaged equations al"C established and the closure problem studied (§1-3). A first detailed study of homogeneous turbulent flows follows (§4). It includes a review of available experimental data and their modeling. The eddy viscosity concept is analyzed in §5 with the l"Csulting ~alar-transport equation models such as the famous K-e model. Reynolds stl"Css models (Chapter 4) require a preliminary consideration of two-point turbulence concepts which are developed in Chapter 3 devoted to homogeneous turbulence. We review the two-point moments of velocity fields and their spectral transforms (§ 1), their general dynamics (§2) with the particular case of homogeneous, isotropie turbulence (§3) whel"C the so-called Kolmogorov's assumptions are discussed at length.

Download or read book The Finding Guide to AIAA Meeting Papers written by American Institute of Aeronautics and Astronautics. Technical Information Service and published by . This book was released on 1981 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Paper written by and published by . This book was released on 1993 with total page 558 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Incompressible Flow of the Three dimensional Turbulent Boundary Layer on the Floor of Curved Channels written by Gerald Peter Francis and published by . This book was released on 1965 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Calculation of Three Dimensional Turbulent Wake boundary Layer Mixing Flows written by M. Nasrullah and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ASME Technical Papers written by and published by . This book was released on with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydraulic Research in the United States written by and published by . This book was released on 1961 with total page 674 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Engineering Index Annual written by and published by . This book was released on 1988 with total page 2282 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its creation in 1884, Engineering Index has covered virtually every major engineering innovation from around the world. It serves as the historical record of virtually every major engineering innovation of the 20th century. Recent content is a vital resource for current awareness, new production information, technological forecasting and competitive intelligence. The world?s most comprehensive interdisciplinary engineering database, Engineering Index contains over 10.7 million records. Each year, over 500,000 new abstracts are added from over 5,000 scholarly journals, trade magazines, and conference proceedings. Coverage spans over 175 engineering disciplines from over 80 countries. Updated weekly.

Download or read book Journal of Turbomachinery written by and published by . This book was released on with total page 852 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Viscous inviscid Interaction Method Including Wake Effects for Three dimensional Wing body Configurations written by and published by . This book was released on 1981 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Aerothermodynamics of Aircraft Gas Turbine Engines written by Gordon C. Oates and published by . This book was released on 1978 with total page 830 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1996 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: