Date of Award

Spring 1987

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Mechanical Engineering

Committee Director

Robert L. Ash

Committee Member

Thomas B. Gatski

Committee Member

Chester Grosch

Committee Member

Surendra N. Tiwari

Committee Member

Ernst von Lavente

Abstract

A numerical simulation of vortex breakdown using the time-dependent Navier-Stokes equations was performed. Unlike previous studies, the numerical algorithm, formulated in terms of the velocity and vorticity, was not restricted to axisymmetric flows. Prototype vortices were parameterized in terms of their Reynolds number and Rossby number. Two cases were studied extensively. In one case, a vortex was imbedded in a uniform free stream. In the other case, the axial velocity of the free stream was decelerated in the streamwise direction. For both cases breakdown occurred when the Rossby number was below a critical value. Vortex lines, particle traces and velocity vector projections of the resulting solutions have been developed. Contour plots of vorticity, velocity and pressure are presented, and the streamwise variation of the rates of change of energy and enstrophy were examined. The computational results have been compared with observations, in terms of flow structures and vortex breakdown. Previous numerical investigations have also been discussed.

DOI

10.25777/f6z1-5s67

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