Zhigang Liu

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Civil and Environmental Engineering


Dr. Gregory A. Kopp


A 2-D, high-resolution, vortex particle method was implemented, and its validity and capabilities were demonstrated through comparisons with experimental and numerical data available in the literature for flows around bluff bodies. A series of simulations of the flow around flat plates with various nosings and elongation ratios were performed. The resultant Stc map (variation of chord-based Strouhal number, Stc, with elongation ratio, d t , and nosing angle, 6 ) reveals that there are an upper and a lower limit for Stc variations, and, by changing the separation angle at the leading edge, the transition between them appears to be continuous. For plates with a smaller separation angle at the leading edge, Stc increases almost linearly with dt after a jump, and eventually makes transition to a horizontal variation. From the analyses of mean flow characteristics, visualizations of the vorticity field, and quantitative analyses of identified vortices, the effects of geometry on a number of flow properties were identified, based on

which a detailed description of the mechanics leading to various behaviors of Stc is given. It is the alternate predominance of the leading- and trailing-edge shedding in the overall shedding process that leads to the linear and horizontal variations, and abrupt jumps of Stc. When the trailing-edge shedding is in control, the shedding frequency jumps to a higher value and Stc tends to follow a linear variation. When the leading-edge shedding predominates, Stctends to follow a horizontal variation.



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