Publication

Abstract : Visualization experiments are conducted in a water channel to investigate the wake vortex characteristics of a flat plate and convex and concave curved plates. Three parameters - vortex size (Sv), vortex length (Lv), and Strouhal number (St) - are investigated in this study to deduce the effect of plate curvature and orientation. These parameters are estimated for both the upper and lower vortices by keeping the chord length (Lc) fixed and changing the plate diameter (D). Various plate configurations are demonstrated by altering the Lc/D ratio from 0 to 1; Lc/D=0, 6/13, 3/4, and 1. The Reynolds number (Re) based on chord length remains unchanged at 5,878 throughout the analysis. For each case of the Lc/D ratio, the angle of flow incidence of the plate (α) is varied from 0° to 30° in steps of 5°. For the convex plate, the combined effect of curvature and orientation is found to enhance the vortex shedding frequency by 70.7%, whereas vortices shrink by 26.71%, and the vortex length is reduced by 25.38%. The manipulations achieved for concave plates reveal comparatively lesser enhancement in shedding frequency; however, concave surfaces are observed to be more suitable for stretching the vortices toward the downstream. The modifications thus achieved have significant practical relevance in various applications. A shedding mechanism that partially interrupts Gerrard's mechanism is also found to operate with concave plate configurations. © 2022 American Society of Civil Engineers.