Experimental Study of Turbulent Concentration Flow Field in the Wake of a Bluff Body

Abstract

Experiments were conducted to determine the turbulent concentration field in the wake of a normal flat plate. Dye was introduced behind the plate as the tracer. The measurement of the dye concentration was carried out using an optical colorimeter in the near wake, covering a distance of five to thirty plate widths downstream of the body. The mean, r.m.s., and intermittency profiles of the concentration field were obtained at a number of cross sections. Phase averaging was also carried out to determine the structure of the large scale eddies. Typical maximum concentration levels in the core of the eddies were found to be two to four times larger than the corresponding mean values. The widths of the concentration profiles in the near wake are 1.5 to 2.5 times wider than the corresponding widths of the velocity profiles. The present dye concentration data obtained for the normal flat plate are unique and complement a small number of previous experimental investigations of the scalar field based on temperature measurements in the wake of circular cylinders.