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Bluff body flows in the presence of a free surface


Valluri, Siddhartha (1996) Bluff body flows in the presence of a free surface. Dissertation (Ph.D.), California Institute of Technology.


An experimental study is performed in a water tunnel (Re = 40,000 to Re = 60,000) to study the interaction between the wake of a circular disk and the free surface. The deformation of the free surface is correlated with the behavior of the wake by utilizing surface pictures, wake flow visualization, drag measurement and Digital Particle Image Velocimetry techniques. It is observed that the wake can exist in two modes with different stabilities. The flow can switch between these two modes and the switching process exhibits hysteresis. The topological differences between these modes and their relation to the observed surface patterns are discussed. The changes in the wake are reflected by an increase in Cd which reaches a maximum value when the upper edge of the disk is 0.125 diameters from the surface. Comparison is also made with a disk approaching a solid boundary.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Aeronautics
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Roshko, Anatol (advisor)
  • Gharib, Morteza (advisor)
Thesis Committee:
  • Roshko, Anatol (chair)
  • Gharib, Morteza (co-chair)
  • Hornung, Hans G.
  • Leonard, Anthony
  • Wu, Theodore Yao-tsu
Defense Date:9 October 1995
Record Number:CaltechETD:etd-06082007-075443
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2516
Deposited By: Imported from ETD-db
Deposited On:26 Jun 2007
Last Modified:26 Dec 2012 02:52

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