Stability of the Vortex Motion in Oscillating Flow.

Abstract

Previous experimental investigations have shown that the characteristics of flow about a circular cylinder immersed in a time-dependent flow exhibit cycle-to-cycle variations. These variations have been attributed to variations in the spanwise coherence, aspec ratio, nonuniformity of the flow, and random disturbances in the ambient flow. A theoretical investigation was undertaken to examine the stability of the flow characteristics in terms of the initial state of the vortices. An idealized model was devised and the position of the vortex was varied systematically. Results show that finite-precision information about the characteristics of the flow does not lead to finite-precision information at a later stage. In fact, advection of the vortices can give rise to chaotic behavior in the calculated lift and drag forces and in the velocity field. It is concluded that the cycle-to-cycle variations are not entirely due to lack of spanwise coherence and that they are mostly a lack of spanwise coherence and that they are mostly a consequence of the chaotic motion which can result from advection of the vortices in a time-dependent flow. Keywords: Vortex advection; Chaos; Coherence length. (Theses).

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Document Details

Document Type
Technical Report
Publication Date
Dec 01, 1986
Accession Number
ADA176629

Entities

People

  • William T. Mccoy

Organizations

  • Naval Postgraduate School

Tags

Communities of Interest

  • Air Platforms
  • Materials and Manufacturing Processes

DTIC Thesaurus Topics

  • Accuracy
  • Aspect Ratio
  • Boundary Layer
  • Computational Fluid Dynamics
  • Computational Science
  • Convection
  • Engineering
  • Equations
  • Flow Fields
  • Flow Visualization
  • Fluid Dynamics
  • Fluid Flow
  • Mechanical Engineering
  • Potential Flow
  • Reynolds Number
  • Turbulent Mixing
  • Viscous Flow

Readers

  • Atmospheric Science/Meteorology
  • Fluid Dynamics.
  • Wave Propagation and Nonlinear Chaotic Dynamics.