Author: Stanford University. Thermosciences Division. Thermosciences Division
Publisher:
ISBN:
Category :
Languages : en
Pages : 46

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Author: Manuel D. Salas
Publisher: Springer Science & Business Media
ISBN: 9780792355908
Category : Science
Languages : en
Pages : 402

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Turbulence modeling both addresses a fundamental problem in physics, 'the last great unsolved problem of classical physics,' and has far-reaching importance in the solution of difficult practical problems from aeronautical engineering to dynamic meteorology. However, the growth of supercom puter facilities has recently caused an apparent shift in the focus of tur bulence research from modeling to direct numerical simulation (DNS) and large eddy simulation (LES). This shift in emphasis comes at a time when claims are being made in the world around us that scientific analysis itself will shortly be transformed or replaced by a more powerful 'paradigm' based on massive computations and sophisticated visualization. Although this viewpoint has not lacked ar ticulate and influential advocates, these claims can at best only be judged premature. After all, as one computational researcher lamented, 'the com puter only does what I tell it to do, and not what I want it to do. ' In turbulence research, the initial speculation that computational meth ods would replace not only model-based computations but even experimen tal measurements, have not come close to fulfillment. It is becoming clear that computational methods and model development are equal partners in turbulence research: DNS and LES remain valuable tools for suggesting and validating models, while turbulence models continue to be the preferred tool for practical computations. We believed that a symposium which would reaffirm the practical and scientific importance of turbulence modeling was both necessary and timely.

Author: W. Rodi
Publisher: Elsevier
ISBN: 008053094X
Category : Mathematics
Languages : en
Pages : 1029

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Turbulence is one of the key issues in tackling engineering flow problems. As powerful computers and accurate numerical methods are now available for solving the flow equations, and since engineering applications nearly always involve turbulence effects, the reliability of CFD analysis depends increasingly on the performance of the turbulence models. This series of symposia provides a forum for presenting and discussing new developments in the area of turbulence modelling and measurements, with particular emphasis on engineering-related problems. The papers in this set of proceedings were presented at the 5th International Symposium on Engineering Turbulence Modelling and Measurements in September 2002. They look at a variety of areas, including: Turbulence modelling; Direct and large-eddy simulations; Applications of turbulence models; Experimental studies; Transition; Turbulence control; Aerodynamic flow; Aero-acoustics; Turbomachinery flows; Heat transfer; Combustion systems; Two-phase flows. These papers are preceded by a section containing 6 invited papers covering various aspects of turbulence modelling and simulation as well as their practical application, combustion modelling and particle-image velocimetry.

Author: Debora Alice Compton
Publisher:
ISBN:
Category :
Languages : en
Pages : 222

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In order to improve predictions of flow behavior in numerous applications there is a great need to understand the physics of three-dimensional turbulent boundary layers, dominated by near-wall behavior. To that end, an experiment was performed to measure near-wall velocity and Reynolds stress profiles in a pressure-driven three-dimensional turbulent boundary layer. The flow was achieved by placing a 30 deg wedge in a straight duct in a wind tunnel, with-additional pressure gradient control above the test surface. An initially two-dimensional boundary layer (Re approx. equal 4000) was exposed to a strong spanwise pressure gradient. At the furthest downstream measurement locations there was also a fairly strong favorable pressure gradient. Measurements were made using a specially-designed near-wall laser Doppler anemometer (LDA), in addition to conventional methods. The LDA used short focal length optics, a mirror probe suspended in the flow, and side-scatter collection to achieve a nearly spherical measuring volume approximately 35 microns in diameter. Good agreement with previous two-dimensional boundary layer data was achieved. The three-dimensional turbulent boundary layer data presented include mean velocity measurements and Reynolds stresses, all extending well below y(+) = 10, at several profile locations. Terms of the Reynolds stress transport equations are calculated at two profile locations. The mean flow is nearly collateral at the wall. Turbulent kinetic energy is mildly suppressed in the near-wall region and the shear stress components are strongly affected by three-dimensionality. As a result, the ratio of shear stress to turbulent kinetic energy is suppressed throughout most of the boundary layer. The angles of stress and strain are misaligned, except very near the wall (around y(+) = 10) where the angles nearly coincide with the mean flow angle.

Author: Jean Piquet
Publisher: Springer Science & Business Media
ISBN: 9783540654117
Category : Technology & Engineering
Languages : en
Pages : 778

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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.

Author: American Institute of Aeronautics and Astronautics
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 990

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Author:
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 542

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Author:
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 654

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Author: Cameron Tropea
Publisher: Springer Science & Business Media
ISBN: 3540251413
Category : Science
Languages : en
Pages : 1570

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Accompanying DVD-ROM contains ... "all chapters of the Springer Handbook."--Page 3 of cover.

Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 358

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