Some Comments on the Modeling of the Turbulent Wake of a Self-Propelled Body in a Stratified Fluid
Some Comments on the Modeling of the Turbulent Wake of a Self-Propelled Body in a Stratified Fluid

Author: Edward Y. T. Kuo

Publisher:

Published: 1972

Total Pages: 14

ISBN-13:

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The modeling of the turbulent wake of a self-propelled body in a stratified fluid is discussed. The scaling parameter is taken to be the internal Froude number, using the speed and diameter of the body and Vaisala frequency of the fluid. The ratio of the time for the wake to collapse to the characteristic time of the turbulence is related to model scale when the wake is turbulent up to and including the collapse. A number of criteria for turbulent wake are discussed. Numerical estimates are made, assuming typical values of the model speed and of the Vaisala frequency, of the minimum model size necessary for the existence of a turbulent wake at collapse.

Turbulent Wakes in a Stratified Fluid. Part 1: Model Development, Verification, and Sensitivity to Initial Conditions
Turbulent Wakes in a Stratified Fluid. Part 1: Model Development, Verification, and Sensitivity to Initial Conditions

Author: W. S. Lewellen

Publisher:

Published: 1974

Total Pages: 134

ISBN-13:

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A computational model has been developed for the turbulent wake of a body moving through a stably stratified fluid. Details of the wake growth, collapse and generation of internal waves were examined by the application of a second-order closure approach to turbulent flow developed at A.R.A.P. over the past few years. Predictions of the model have been verified by comparison with a wide variety of wake flows including wakes with no momentum, wakes with axial momentum, wakes with angular momentum, and for wakes in both stratified and unstratified fluids. A sensitivity investigation reveals that the primary variable affecting the strength of the generated internal waves is the initial Richardson number, with the first local maximum of the vertical height of the wake scaling inversely with the 1/8th power of the initial Richardson number.

Modeling, Simulation and Optimization of Complex Processes
Modeling, Simulation and Optimization of Complex Processes

Author: Hans Georg Bock

Publisher: Springer Science & Business Media

Published: 2008-06-19

Total Pages: 665

ISBN-13: 3540794093

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This proceedings volume covers the broad interdisciplinary spectrum of scientific computing and presents recent advances in theory, development of methods, and applications in practice.

Experiments on Turbulent Wakes in a Stable Density-stratified Environment
Experiments on Turbulent Wakes in a Stable Density-stratified Environment

Author: Walter P. M. van de Watering

Publisher:

Published: 1969

Total Pages: 74

ISBN-13:

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In a laboratory experiment, turbulent mixed regions were generated in a linearly density-stratified fluid and their behavior was studied. Such regions may occur in nature in the atmosphere and in the ocean. Particularly during their early history, the shape of such regions is influenced by the interacting effects of turbulence and buoyancy, culminating in the occurrence of a maximum thickness and subsequent vertical collapse. A Richardson number (equivalent to the ratio of the characteristic turbulence time and the Vaisala period) was found satisfactorily to correlate the data obtained, together with those previously obtained by other investigators with self-propelled bodies. An estimate is made of the degree of mixing that takes place inside a turbulent mixed region during its growth in stably-stratified surroundings: the effectiveness of this mixing determines the ultimate thickness to which the mixing region collapses. (Author).

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.

Twenty-Fourth Symposium on Naval Hydrodynamics
Twenty-Fourth Symposium on Naval Hydrodynamics

Author: National Research Council

Publisher: National Academies Press

Published: 2003-11-15

Total Pages: 1018

ISBN-13: 0309254701

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This report is part of a series of reports that summarize this regular event. The report discusses research developments in ship design, construction, and operation in a forum that encouraged both formal and informal discussion of presented papers.

Handbook of Turbulence
Handbook of Turbulence

Author: Walter Frost

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 511

ISBN-13: 1468423223

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Turbulence takes place in practically all flow situations that occur naturally or in modern technological systems. Therefore, considerable effort is being expended in an attempt to understand this very complex physical phenome non and to develop both empirical and mathematical models for its description. Such numerical and analytical computational schemes would allow the reliable prediction and design of turbulent flow processes to be carried out. The purpose of this book is to bring together, in a usable form, some of the fundamental concepts of turbulence along with turbulence models and experimental techniques. It is hoped that these have "general applicability" in current engineering design. The phrase "general applicabil ity" is highlighted because the theory of turbulence is still so much in a formative stage that completely general analyses are not available now, nor will they be available in the immediate future. The concepts and models described herein represent the state-of-the art methods that are now being used to give answers to turbulent flow problems. As in all turbulent flow analysis, the methods are a blend of analytical and empirical input, and the reader should be cognizant of the simplification and restrictions imposed upon the methods when applyingthem to physical situations different from those for which they have been developed.