Measurement of tracer concentration in the flow around finite-height cylinders

This paper presents an experimental investigation of mass transfer in the flow around surface mounted finite-height circular cylinders. The study was carried out in a high-pressure closed water channel for cylinders with height-to-diameter ratios of 2.5 and 5.0. The Reynolds number based on the cylinder diameter was 4.4 x 10(4) and 2.2 x 10(4) for these two cylinders respectively, and the approach-flow boundary layer had a thickness of about 10% of the cylinder height. The flow behaviour was visualised by means of tracer addition, using a commercial white emulsion paint, and the spatial and temporal distributions of the tracer concentration were measured using the planar non-intrusive quantitative light sheet (QLS) technique. For tracer injections at different levels upstream of the cylinder and one injection near the bottom downstream of the cylinder, contour plots of the time-averaged concentration as well as of the RMS values are provided in different horizontal planes. Some flow-visualisation films are also presented.