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Mass transfer between the interior surface of small rectangular cavities and the solution flowing past the cavity opening, was investigated by both theoretical and experimental techniques. The boundary integral method was used to calculate the viscous shear stress along the cavity surface under the assumption of Stokes flow for aspect ratios (width:depth) between 0.75:1 and 10:1. It was found that the separation streamline became reattached to the bottom surface of the cavity when the aspect ratio exceeded about 3:1. The Lighthill integral method was used to calculate the local mass transfer rate along the cavity surface and the separation streamline(s). Experimental measurements of the average mass transfer coefficients were made by an electrochemical method in which the Cu test specimen was an anode and formed a soluble surface film of dissolution products in 1M H2SO4. Predictions of the average mass transfer rate along the interior surface agreed with experimental data to within 2.6% for the 1:1 cavity, and to within 14% for the 5:1 geometry. The results are discussed with respect to processing of printed circuit boards to form lines by pattern etching.

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The effect of a single circular impinging fluid jet on hydrodynamic flow and mass transfer in a single through-hole centered at the stagnation point was investigated. Both submerged and unsubmerged jets were studied. Sectioned electrodes were used for direct experimental measurement of local rates of mass transfer and of hydrodynamic shear stress within individual through-holes. The ferricyanide system was used to obtain convective mass transfer rates upon controlled variation of jet Reynolds number, nozzle-to-workpiece distance, through-hole diameter, and aspect ratio. Data were used to establish mass-transfer correlations for both submerged and unsubmerged systems. It was found that the fluid flow in the through-hole corresponded to the hydrodynamic entrance region. A mathematical model of the current and potential distribution was used to identify dimensionless conditions for achieving uniform deposits and for insuring adequate convection rates. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 193.61.135.80 Downloaded on 2015-03-13 to IP Vol. 134, No. 5 THE EFFECT OF AN IMPINGING FLUID JET 1173 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 193.61.135.80 Downloaded on 2015-03-13 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 193.61.135.80 Downloaded on 2015-03-13 to IP