Electrochemical measurements of mass transfer between a sphere and liquid in motion at high Péclet numbers

Experimental studies of the effect of a transverse velocity gradient on the mass transfer between a fixed solid spherical particle and liquid and of the mass-transfer intensity between solid sphere and liquid in a uniform flow have been carried out. Both types of flow were formed between two rotating circular cylinders parallel to each other and separated by a distance of 10mm. The following experimental procedures were applied : a method of stroboscopic visualization to measure velocity profiles, and an electrochemical method to measure the mass-transfer intensity between sphere and liquid. Results were obtained for a wide range of the relevant dimensionless parameters, viz the Reynolds and PBclet numbers specified for each case appropriately. In the case of simple shear flow these ranges are: 0.03 Nu $Nu = 1.134 Pe^{*\frac{1}{3}}$ obtained theoretically by Batchelor (1979) for an ambient pure straining motion with the assumptions that Re* [Lt ] 1 and Pe* [Gt ] 1. In the case of a uniform flow the ranges of the dimensionless parameters are 0.4 Pe Nu Nu ∝ Pe 1/3 obtained by Aksel'rud (1953) and Acrivos & Taylor (1962).