Flat Plate Reduction In A Water Tunnel Using Riblets
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Author | : L. W. Reidy |
Publisher | : |
Total Pages | : 22 |
Release | : 1987 |
Genre | : |
ISBN | : |
Streamwise microgroove surface modifications, known as riblets, are known to alter the structure of the turbulent boundary layer such that the skin friction drag over the surface is reduced. For this investigation, velocity profile measurements were used to calculate the drag on a flat plate, both with and without riblets, in a high-speed water tunnel. The vinyl riblet surface produced a maximum drag reduction of 8.1% + or - 2.5% at a nondimensional groove spacing, + or - of 13.1. If the results obtained in the laboratory can be realized for torpedoes and other submersibles, significant improvements in vehicle speed or fuel economy will be achieved.
Author | : Laurel W. Reidy |
Publisher | : |
Total Pages | : 13 |
Release | : 1988 |
Genre | : |
ISBN | : |
Two hydrodynamic experiments were conducted to measure drag reduction using riblets in turbulent boundary layers. The first was an external boundary layer experiment using a flat plate in a water tunnel, and the second was an internal boundary layer experiment using a 6-inch diameter pipe. Both experiments used adhesive-backed, vinyl, riblet film, manufactured by the 3M Co., with height and spacing of the symmetric v-grooves equal to 0.003 in. For the flat plate test, free stream velocities ranged from 6.5 ft/sec to 20 ft/sec, and Re sub theta ranged from 1260-7040. The results are in good agreement with aerodynamic data, and show a maximum drag reduction of 8.1% + or - 2.5% at s(+) = 13.1. Much larger percentages of friction reduction (approx. 3x as much) were measured with riblets in the pipe. When a drag-reducing polymer solution was used in conjunction with the riblets in the pipe flow, the total drag reduction was approximately equal to the sum of the drag reductions of the two techniques used separately, with some dependence on Reynolds number. Before these pipe flow results can be extended to general situations, further experiments are needed to investigate the boundary layer transition from smooth to riblet surface.
Author | : |
Publisher | : |
Total Pages | : 702 |
Release | : 1995 |
Genre | : Aeronautics |
ISBN | : |
Author | : Russell H. Thomas |
Publisher | : |
Total Pages | : 98 |
Release | : 2002 |
Genre | : Aerodynamical noise |
ISBN | : |
Author | : |
Publisher | : |
Total Pages | : 520 |
Release | : 1987 |
Genre | : Science |
ISBN | : |
Author | : Roland Liebe |
Publisher | : WIT Press |
Total Pages | : 418 |
Release | : 2007 |
Genre | : Science |
ISBN | : 1845640012 |
Do we have an adequate understanding of fluid dynamics phenomena in nature and evolution, and what physical models do we need? What can we learn from nature to stimulate innovations in thinking as well as in engineering applications? Concentrating on flight and propulsion, this unique and accessible book compares fluid dynamics solutions in nature with those in engineering. The respected international contributors present up-to-date research in an easy to understand manner, giving common viewpoints from fields such as zoology, engineering, biology, fluid mechanics and physics. Contents: Introduction to Fluid Dynamics; Swimming and Flying in Nature; Generation of Forces in Fluids - Current Understanding; The Finite, Natural Vortex in Steady and Unsteady Fluid Dynamics - New Modelling; Applications in Engineering with Inspirations From Nature; Modern Experimental and Numerical Methods in Fluid Dynamics.
Author | : Hamid Bellout |
Publisher | : Springer Science & Business Media |
Total Pages | : 583 |
Release | : 2013-11-19 |
Genre | : Science |
ISBN | : 3319008919 |
The theory of incompressible multipolar viscous fluids is a non-Newtonian model of fluid flow, which incorporates nonlinear viscosity, as well as higher order velocity gradients, and is based on scientific first principles. The Navier-Stokes model of fluid flow is based on the Stokes hypothesis, which a priori simplifies and restricts the relationship between the stress tensor and the velocity. By relaxing the constraints of the Stokes hypothesis, the mathematical theory of multipolar viscous fluids generalizes the standard Navier-Stokes model. The rigorous theory of multipolar viscous fluids is compatible with all known thermodynamical processes and the principle of material frame indifference; this is in contrast with the formulation of most non-Newtonian fluid flow models which result from ad hoc assumptions about the relation between the stress tensor and the velocity. The higher-order boundary conditions, which must be formulated for multipolar viscous flow problems, are a rigorous consequence of the principle of virtual work; this is in stark contrast to the approach employed by authors who have studied the regularizing effects of adding artificial viscosity, in the form of higher order spatial derivatives, to the Navier-Stokes model. A number of research groups, primarily in the United States, Germany, Eastern Europe, and China, have explored the consequences of multipolar viscous fluid models; these efforts, and those of the authors, which are described in this book, have focused on the solution of problems in the context of specific geometries, on the existence of weak and classical solutions, and on dynamical systems aspects of the theory. This volume will be a valuable resource for mathematicians interested in solutions to systems of nonlinear partial differential equations, as well as to applied mathematicians, fluid dynamicists, and mechanical engineers with an interest in the problems of fluid mechanics.
Author | : |
Publisher | : |
Total Pages | : 136 |
Release | : 1985 |
Genre | : Technology |
ISBN | : |
Author | : Bharat Bhushan |
Publisher | : Springer Science & Business Media |
Total Pages | : 351 |
Release | : 2012-06-05 |
Genre | : Science |
ISBN | : 364225408X |
This book presents an overview of the general field of biomimetics - lessons from nature. It presents various examples of biomimetics, including roughness-induced superomniphobic surfaces which provide functionality of commercial interest. The major focus in the book is on lotus effect, rose petal effect, shark skin effect, and gecko adhesion. For each example, the book first presents characterization of an object to understand how a natural object provides functionality, followed by modeling and then fabrication of structures in the lab using nature’s route to verify one’s understanding of nature and provide guidance for development of optimum structures. Once it is understood how nature does it, examples of fabrication of optimum structures using smart materials and fabrication techniques, are presented. Examples of nature inspired objects are also presented throughout.
Author | : K.M. Gupta |
Publisher | : CRC Press |
Total Pages | : 640 |
Release | : 2014-11-13 |
Genre | : Science |
ISBN | : 1482257971 |
Introduces Emerging Engineering Materials Mechanical, materials, and production engineering students can greatly benefit from Engineering Materials: Research, Applications and Advances. This text focuses heavily on research, and fills a need for current information on the science, processes, and applications in the field. Beginning with a brief overview, the book provides a historical and modern perspective on material science, and describes various types of engineering materials. It examines the industrial process for emerging materials, determines practical use under a wide range of conditions, and establishes what is needed to produce a new generation of materials. Covers Basic Concepts and Practical Applications The book consists of 18 chapters and covers a variety of topics that include functionally graded materials, auxetic materials, whiskers, metallic glasses, biocomposite materials, nanomaterials, superalloys, superhard materials, shape-memory alloys, and smart materials. The author outlines the latest advancements, including futuristic plastics, sandwich composites, and biodegradable composites, and highlights special kinds of composites, including fire-resistant composites, marine composites, and biomimetics. He also factors in current examples, future prospects, and the latest research underway in materials technology. Contains approximately 160 diagrams and 85 tables Incorporates examples, illustrations, and applications used in a variety of engineering disciplines Includes solved numerical examples and objective questions with answers Engineering Materials: Research, Applications and Advances serves as a textbook and reference for advanced/graduate students in mechanical engineering, materials engineering, production engineering, physics, and chemistry, and relevant researchers and practicing professionals in the field of materials science.