EXPERIMENTAL-STUDY OF TURBULENT CONCENTRATION FLOW-FIELD IN THE WAKE OF A BLUFF-BODY

Experiments were conducted to determine the turbulent concentration fi eld in the wake of a normal flat plate. Dye was introduced behind the plate as the tracer. The measurement of the dye concentration was carr ied out using an optical colorimeter in the near wake, covering a dist ance of five to thirty plate widths downstream of the body. The mean, r.m.s., and intermittency profiles of the concentration field were obt ained at a number of cross sections. Phase averaging was also carried out to determine the structure of the large scale eddies. Typical maxi mum concentration levels in the core of the eddies were found to be tw o 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 wi der than the corresponding widths of the the velocity profiles. The pr esent dye concentration data obtained for the normal pat plate are uni que and complement a small number of previous experimental investigati ons of the scalar field based on temperature measurements in the wake of circular cylinders.