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Direct numerical simulations of unsteady separated flows using vortex methods


Koumoutsakos, Petros D. (1993) Direct numerical simulations of unsteady separated flows using vortex methods. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/TCQ9-9C86.


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Numerical simulations are presented for viscous incompressible flows with and without solid wall boundaries. Our numerical method is based on vortex methods. The classical inviscid scheme is enhanced to account for viscous effects via the method of particle strength exchange. The method is extended to account for the enforcement of the no-slip boundary condition as well by appropriately modifying the strength of the particles. Computations are possible for extended times by periodically remeshing the vorticity field.

The particles are advanced using the Blot-Savart law for the evaluation of the velocity. Computations are made using up to [...](10[superscript 6]) vortex particles by efficiently implementing the method of multipole expansions for vector computer architectures to obtain an [...](N) algorithm.

The method is used to simulate the inviscid evolution of an elliptical vortex in an unbounded fluid as well as unsteady separated flows around circular cylinders for a wide range of Reynolds numbers (40 - 9500). Direct comparisons are made of the results of the present method with those from a variety of theoretical, computational and experimental studies. The results exhibit the robustness and validity of the present method and allow to gain physical insight as to vorticity formation and its relation to the forces experienced by the body.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Aeronautics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Leonard, Anthony
Thesis Committee:
  • Leonard, Anthony (chair)
  • Roshko, Anatol
  • Pullin, Dale Ian
  • Hornung, Hans G.
  • Knowles, James K.
Defense Date:6 August 1992
Non-Caltech Author Email:petros (AT)
Record Number:CaltechETD:etd-11122003-082957
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:4516
Deposited By: Imported from ETD-db
Deposited On:12 Nov 2003
Last Modified:21 Dec 2019 02:22

Thesis Files

PDF (Koumoutsakos_pd_1993.pdf) - Final Version
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