Download or read book The Growth of a Turbulent Wake in a Density stratified Fluid written by Walter P. M. van de Watering and published by . This book was released on 1966 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: The force of gravity causes a turbulent wake in a density-stratified fluid to eventually cease its vertical growth and then to collapse towards its horizontal midplane. In the present investigation this phenomenon was studied experimentally. The turbulent wake was created by means of a spiral paddle, agitated by a pendulum-type arrangement outside a transparent lucite tank. Data were obtained from tracings of the motion pictures taken by a 16 mm movie camera. Both the pendulum arrangement and the paddle diameter were varied to find the possible influence of the experimental conditions. It was observed that the initial rate of growth in the vertical direction is constant, depending primarily on the density gradient and the agitation mechanism (i.e. pendulum and paddle diameter). This initial rate of growth of the wake, the maximum vertical thickness of the wake, the time at which collapse begins and the turbulence intensity within the wake at that time, were all correlated with the Vaisala frequency, resulting in three important constants which seemed to be independent of the experimental conditions. (Author).
Download or read book The Shape of Two dimensional Turbulent Wakes in Density stratified Fluids written by and published by . This book was released on 1968 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of an analytical and experimental investigation of the rate of growth of the zone of turbulent mixing behind a two-dimensional circular cylinder are presented. The analytical phase of the study formulated a dynamical model for a parcel of fluid subjected to inertia, turbulent damping, and gravity restoring forces. The experiments were conducted in a tank 120 in. long and 4.5 in. wide which was filled to a depth of 18 in. with a fluid having a linear density gradient. The cylinder was towed at mid-depth by a variable speed motor-pulley system. A record of wake growth behind the cylinder was made by means of motion pictures of an aluminum pigment tracer in the fluid. The Reynolds number ranged from 1300 to 3500 and densimetric Froude numbers varied from 5 to 20. The density stratification was found to exert a strong inhibiting force on the wake growth. Using the dynamical model to correlate experimental data, the mixing length in the turbulent zone was found to decrease with increasing density stratification. (Author).
Download or read book Experiments on Turbulent Wakes in a Stable Density stratified Environment written by Walter P. M. van de Watering and published by . This book was released on 1969 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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).
Download or read book Turbulent Wakes in a Stratified Fluid Part 1 Model Development Verification and Sensitivity to Initial Conditions written by W. S. Lewellen and published by . This book was released on 1974 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book High Resolution Simulation of the Turbulent Wake Behind a Sphere in a Stratified Fluid written by Matthew Bronson De Stadler and published by . This book was released on 2013 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: The wake of a bluff body is significantly modified by the presence of a stable density stratification. Buoyancy effects introduce a complex coupling between kinetic and potential energy which results in a significantly longer wake lifetime, internal wave radiation, and long lived coherent structures. This dissertation presents results obtained from high resolution numerical simulations of stratified turbulent wakes. The dissertation is divided into two parts. The first part of the dissertation uses the well established temporal approximation to simulate from the near wake to the far wake. In this part of the dissertation, the effect of the Prandtl number on a stratified turbulent wake was considered. For 0.2 Pr
Download or read book Turbulent Wakes in Density Stratified Fluids of Finite Extent written by Edmund A. Prych and published by . This book was released on 1964 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results are presented of an investigation of the effects of a free surface and density stratification of the turbulent transfer of mass and momentum in two-dimensional wakes. The effect of depth of submergence on the drag of a twodimensional body was also investigated.
Download or read book The Shape of Two dimensional Turbulent Wakes in Density stratified Fluids written by Roy Hayden Monroe and published by . This book was released on 1968 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of an analytical and experimental investigation of the rate of growth of the zone of turbulent mixing behind a two-dimensional circular cylinder are presented. The analytical phase of the study formulated a dynamical model for a parcel of fluid subjected to inertia, turbulent damping, and gravity restoring forces. The experiments were conducted in a tank 120 in. long and 4.5 in. wide which was filled to a depth of 18 in. with a fluid having a linear density gradient. The cylinder was towed at mid-depth by a variable speed motor-pulley system. A record of wake growth behind the cylinder was made by means of motion pictures of an aluminum pigment tracer in the fluid. The Reynolds number ranged from 1300 to 3500 and densimetric Froude numbers varied from 5 to 20. The density stratification was found to exert a strong inhibiting force on the wake growth. Using the dynamical model to correlate experimental data, the mixing length in the turbulent zone was found to decrease with increasing density stratification. (Author).
Download or read book Technical Abstract Bulletin written by and published by . This book was released on with total page 912 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Mechanics written by M. Hetenyi and published by Springer Science & Business Media. This book was released on 2013-11-27 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the Proceedings of the Twelfth International Congress of Applied Mechanics, held at Stanford University on August 26 to 31, 1968. The Congress was organized by the International Union of Theoretical and Applied Mechanics; members of the IUTAM Congress Committee and Bureau are listed under Congress Organization. The members of the Stanford Organizing Committee, which was responsible for the detailed organization of the Congress, are also given, as are the names of the sponsors and the industrial and educational organizations that contributed so generously to the financial support of the meeting. Those attending the Congress came from 32 countries and totaled 1337 persons, plus wives and children. A list of the registered participants is included in the volume. The technical sessions of the Congress comprised four General Lectures and 281 contributed papers, the latter being presented in groups of five simultaneous sessions. The final choice of the contributed papers was made on the basis of abstracts by an International Papers Commit tee of IUTAM consülting of G. K. BATCHELOR, E. BECKER, N. J. HOFF, and W. T. KOlTER.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1981 with total page 1370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Mixing of a Stratified Fluid in a Two dimensional Turbulent Wake written by Edmund A. Prych and published by . This book was released on 1963 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Two dimensional Turbulent Momentum Wakes in Density Stratified Fluids written by Robert Anton Froebel and published by . This book was released on 1964 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Second Order Turbulent Modeling Applied to Momentumless Wakes in Stratified Fluids written by W. Stephen Lewellen Milton Teske and published by . This book was released on 1973 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: The technique of second-order closure for turbulence modeling is used to treat the growth and decay of turbulence, and the generation of internal waves behind a submarine moving at constant velocity through a stratified ocean. A computer model based on the solution of five partial differential equations and approximating nine others is generated. Required model coefficients are obtained by comparison with data obtained from laboratory flows and the atmospheric surface layer. The model is verified by comparison with Naudascher's wake data in the limit of vanishing stratification; with Wu's observations in the limit of starting with a uniformly mixed region in a strongly stratified fluid; and with Hartman and Lewis's analytical predictions in the limit of a small perturbation to the ambient linear density gradient and vanishing turbulence. (Modified author abstract).
Download or read book Turbulent Wake in a Stratified Medium Trubulentnyy Sled V Stratifitsirovannoy Srede written by A. T. Onufriyev and published by . This book was released on 1977 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The article discusses the problem of determining the shape of a turbulent wake formed behind a self-propelled body in a medium with a density variable in the direction of action of gravity. A schematic picture of the development of the wake behind the moving object is as follows: at the outset, the diffusion is the same in all directions, and the wake expands symmetrically; with increasing distance from the object, the diffusion becomes strongly anisotropic, it decreases in the vertical direction under the action of gravity, and the wake assumes a flattened shape; in the volume occupied by the wake, turbulent mixing within the wake gives rise to a more homogeneous density distribution than in the ambient medium; this volume of liquid is no longer in a state of equilibrium and, acted upon by gravity, tends to return to this state; the wake collapses, and this is accompanied by its further expansion in the horizontal direction and excitation of internal waves.
Download or read book ASME Technical Papers written by and published by . This book was released on 1974 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government wide Index to Federal Research Development Reports written by and published by . This book was released on 1967-04 with total page 1078 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NBS Special Publication written by and published by . This book was released on 1968 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:
