Free-surface/vorticity interaction

Approved for public release; distribution is unlimited. === The unsteady flow phenomena resulting from the interaction of wakes and vortices with the free surface are of particular importance in naval hydrodynamics. Ship and submarine wakes produce a three-dimensional complex signature, comprised o...

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Main Author: Carroll, John B.
Other Authors: Sarpkaya, Turgut
Language:en_US
Published: Monterey, California. Naval Postgraduate School 2014
Online Access:http://hdl.handle.net/10945/39925
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spelling ndltd-nps.edu-oai-calhoun.nps.edu-10945-399252014-12-24T04:04:00Z Free-surface/vorticity interaction Carroll, John B. Sarpkaya, Turgut Naval Postgraduate School (U.S.) Department of Mechanical Engineering Approved for public release; distribution is unlimited. The unsteady flow phenomena resulting from the interaction of wakes and vortices with the free surface are of particular importance in naval hydrodynamics. Ship and submarine wakes produce a three-dimensional complex signature, comprised of a narrow dark band bordered by two bright lines in synthetic-aperture-radar (SAR) images. The dark band signifies the suppression of waves at the Bragg frequency as a consequence of the interaction between the free surface and the imposed vorticity. In the present investigation, the vorticity field is provided by a single tip vortex generated by an airfoil. The results, obtained with an LDV, have shown that the free surface redistributes part or all of the normal turbulent kinetic energy into streamwise and spanwise components. The turbulent kinetic energy first decreases sharply with increasing vertical distance from the vortex and then remains nearly constant within a thin layer below the 'roughened' free surface. The results explain the longevity of the structures and lend further credence to the simulation of near-surface structures via vortex- or contour-dynamics. 2014-03-26T23:23:51Z 2014-03-26T23:23:51Z 1993-09 Thesis http://hdl.handle.net/10945/39925 en_US This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, it may not be copyrighted. Monterey, California. Naval Postgraduate School
collection NDLTD
language en_US
sources NDLTD
description Approved for public release; distribution is unlimited. === The unsteady flow phenomena resulting from the interaction of wakes and vortices with the free surface are of particular importance in naval hydrodynamics. Ship and submarine wakes produce a three-dimensional complex signature, comprised of a narrow dark band bordered by two bright lines in synthetic-aperture-radar (SAR) images. The dark band signifies the suppression of waves at the Bragg frequency as a consequence of the interaction between the free surface and the imposed vorticity. In the present investigation, the vorticity field is provided by a single tip vortex generated by an airfoil. The results, obtained with an LDV, have shown that the free surface redistributes part or all of the normal turbulent kinetic energy into streamwise and spanwise components. The turbulent kinetic energy first decreases sharply with increasing vertical distance from the vortex and then remains nearly constant within a thin layer below the 'roughened' free surface. The results explain the longevity of the structures and lend further credence to the simulation of near-surface structures via vortex- or contour-dynamics.
author2 Sarpkaya, Turgut
author_facet Sarpkaya, Turgut
Carroll, John B.
author Carroll, John B.
spellingShingle Carroll, John B.
Free-surface/vorticity interaction
author_sort Carroll, John B.
title Free-surface/vorticity interaction
title_short Free-surface/vorticity interaction
title_full Free-surface/vorticity interaction
title_fullStr Free-surface/vorticity interaction
title_full_unstemmed Free-surface/vorticity interaction
title_sort free-surface/vorticity interaction
publisher Monterey, California. Naval Postgraduate School
publishDate 2014
url http://hdl.handle.net/10945/39925
work_keys_str_mv AT carrolljohnb freesurfacevorticityinteraction
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