Free-Surface/Vorticity Interaction

Abstract

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. Surface disturbances, Scars, Striations, Trailing vortices, Vortex dynamics

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Document Details

Document Type
Technical Report
Publication Date
Sep 01, 1993
Accession Number
ADA273263

Entities

People

  • John B. Carroll

Organizations

  • Naval Postgraduate School

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Boundary Layer
  • Channel Flow
  • Classification
  • Computational Fluid Dynamics
  • Dynamics
  • Flow Visualization
  • Fluid Flow
  • Fluid Mechanics
  • Kinetic Energy
  • Mechanical Engineering
  • Predictive Modeling
  • Security
  • Simulations
  • Synthetic Aperture Radar
  • Trailing Vortices
  • Two Dimensional
  • United States

Fields of Study

  • Physics

Readers

  • Aerodynamics.
  • Atmospheric Science / Meteorology, specifically Wind Wave Turbulence.
  • Computer Vision.