Three-dimensional flow and surface visualization using hydrogen bubble technique
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A modified hydrogen bubble technique is developed for simultaneous three-dimensional flow visualization and surface visualization on bluff bodies. A detailed description of the technique implementation and operating principles is presented. The technique is validated on two geometries: (1) a uniform circular cylinder for ReD = 1,050 and 2,100; and (2) a dual-step cylinder for ReD = 2,100, D/d = 2, and L/D = 0.5. The results demonstrate that flow visualizations effectively capture intricate three-dimensional wake vortex development including the formation of streamwise structures and vortex interactions in the wake of a dual-step cylinder. The surface visualizations capture boundary layer separation and its variation along the span of the models. Moreover, the results reveal complex three-dimensional surface flow patterns, shedding light on the topology of vortical structures forming near dual-step cylinder junctions.
KeywordsFlow visualization Surface visualization Turbulent vortex shedding Hydrogen bubble technique
The authors gratefully acknowledge the Natural Sciences and Engineering Research Council of Canada (NSERC) for the funding of this work.
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