Turbulent Wake Behind a Self-Propelled Body
Turbulent Wake Behind a Self-Propelled Body

Author: Toshi Kubota

Publisher:

Published: 1975

Total Pages: 39

ISBN-13:

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The wake behind a self-propelled body is studied for laminar and turbulent cases. For the laminar wake, asymptotic solutions are obtained with and without swirl. For the turbulent wake with the eddy-viscosity model, the solution is obtained from the laminar flow solution by transformation that reduces the turbulent-flow equation to the equation for laminar flow. With the mixing-length model for the turbulent shear stress, the far-wake solution becomes that of non-linear eigenvalue problem. These two models yield results that do not agree with experimental results. The far-wake solution is formulated based on a two-equation model for turbulent shear--turbulent energy and dissipation--with an additional assumption of negligible turbulence production from the mean flow.

Turbulent Wake Behind Slender Bodies Including Self-Propelled Configurations
Turbulent Wake Behind Slender Bodies Including Self-Propelled Configurations

Author: R. C Swanson (Jr)

Publisher:

Published: 1974

Total Pages: 88

ISBN-13:

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The turbulent wakes behind a streamlined drag body, a jet-propelled body, and a propeller-driven body are studied experimentally in a subsonic wind tunnel at a principal nominal free-stream velocity of 206 ft/sec. Mean flow data taken downstream of the sterns of these bodies include velocity and static pressure distributions. The stream-wise variation of the maximum values of axial turbulence intensity and radial shear stress are also presented. The mean flow data for the wake behind the drag body compare favorably with previous experiments and establish a rigid reference for the wakes behind slender, self-propelled configurations. The downstream rate of decay is essentially the same for the drag and propeller-driven bodies, whereas the decay for the jet-propelled body is substantially faster.

Engineering Turbulence Modelling and Experiments 5
Engineering Turbulence Modelling and Experiments 5

Author: W. Rodi

Publisher: Elsevier

Published: 2002-08-21

Total Pages: 1029

ISBN-13: 008053094X

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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.

Calculations of the Turbulent Wake Behind a Slender Self-Propelled Double-Body and Comparisons with Experiment
Calculations of the Turbulent Wake Behind a Slender Self-Propelled Double-Body and Comparisons with Experiment

Author: Thomas F Swean (Jr)

Publisher:

Published: 1987

Total Pages: 44

ISBN-13:

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The parabolic, incompressible, time-averaged Navier-Stokes equations together with a two-equation (K, epsilon) model of turbulence are used to numerically simulate the wake downstream of a slender double-body. The equations are solved using the finite-element method and the results are compared to experimental data for both unpropelled and self-propelled configurations. With the exception of certain localized phenomena, the calculations and experiments are found to be in good agreement for the mean velocity components. the turbulence kinetic energy, and the Reynolds shear stresses. The noteworthy exception for the unpropelled configuration is the prediction of a rather strong region of production of turbulence in the near wake which is not evident in the data. The simulation of the self-propelled wake is in good agreement with the data for the mean velocity components. There is also acceptable agreement for the turbulence parameters over most of the wake cross-section except near the radius of the propeller tips. Severe qualitative and quantitative discrepancies in this region are possibly due to the presence of periodic components in the data. Keywords: Finite-element analysis.

Investigation of the Turbulent Properties of the Wake Behind Self-propelled, Axisymmetric Bodies
Investigation of the Turbulent Properties of the Wake Behind Self-propelled, Axisymmetric Bodies

Author: C. C. Chieng

Publisher:

Published: 1974

Total Pages: 224

ISBN-13:

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The turbulent wakes behind a streamlined drag body, a jet propelled body and a propeller-driven body are studied experimentally in the VPI Stability Wind Tunnel at a nominal free stream velocity of 206 ft/sec. The turbulence properties investigated are axial, radial, and tangential turbulence intensities, and radial and tangential shear stresses.

Flow in the Wake of Self-propelled Bodies and Related Sources of Turbulence
Flow in the Wake of Self-propelled Bodies and Related Sources of Turbulence

Author: Eduard Naudascher

Publisher:

Published: 1965

Total Pages: 36

ISBN-13:

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In the steady-state counterpart of the wake behind a totally immersed, self-propelled body, simulated in an air tunnel by a concentric nozzle and disk, measurements were made of mean-flow velocity and pressure, turbulence intensities in the three co-ordinate directions, turbulent shear, and mean temporal gradient and auto-correlation of the axial-velocity flucutations. Through the equations of momentum and energy for the mean and the turbulent motion, the experimental data were used to verify the condition of self-propulsion and the accuracy of measurement, and to provide a picture of the force field and the process of energy transformation. The variation of the principal flow characteristics was analysed with the aid of appropriate hypotheses as to the transport mechanism and the structure of the turbulence. (Author).

Turbulent Flows
Turbulent Flows

Author: Jean Piquet

Publisher: Springer Science & Business Media

Published: 2013-04-17

Total Pages: 767

ISBN-13: 3662035596

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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.