Transient convective diffusion to a circular sink at finite Peclet number

Abstract

Theory by Geshev and Safarova [P.I. Geshev, N.S. Safarova, Angular and transient characteristics of circular electrochemical friction probes, Int. J. Heat Mass Transfer 42 (1999) 3183–3188] of transient mass transfer from shear flow to circular sink is checked over broad range of Peclet number by electrodiffusion experiments with varied sink radius (0.1–1 mm), shear rate (0.5–200 s −1), and diffusivity (4 × 10 −11–7 × 10 −10 m 2 s −1). This theory is confirmed within 2% accuracy for steady-state mass-transfer coefficients but transient characteristics are completely wrong. Area, perimeter, and transport length of circular probes are autocalibrated by fitting a semi-empirical model on the transient data at known shear rates. Well-calibrated probes provide data on diffusion coefficient and wall shear rate with accuracies of 2% and 5%, respectively.