MASS-TRANSFER TO A CHANNEL WALL DOWNSTREAM OF A CYLINDER

The electrochemical method is used to measure the mass-transfer to a c hannel wall downstream of a cylinder. For Reynolds numbers based on cy linder diameter Re > 50, the flow is unsteady, and the mass-transfer r ate is a function of time. When 50 < Re < 200, the mass-transfer rate is periodic with a frequency in the range of 1-3 Hz. When the ratio of cylinder diameter d to channel height h is 0.25, the Strouhal number is measured to be 0.27 +/- 0.02, and when d/h = 0.51, the Strouhal num ber is 0.49 +/- 0.01. The average mass-transfer rate at various positi ons downstream of the cylinder is reported. Experiments are compared t o two-dimensional numerical simulations. The simulated and experimenta l variations of Nusselt number with position and Re contain similar fe atures, but exact agreement is not found. (C) 1997 Elsevier Science Lt d.