Investigative Study of Local Sherwood Numbers Using Phase Measurement Interferometry

Abstract

This paper investigates the relationship between mass and momentum transport. This study of mass transfer is an important design consideration when looking at engineering processes such as evaporation, chemical reactions, corrosion and mixing. Little is know about the relationship. Using the non-intrusive optical technique of Electronic Speckle Pattern Interferometry (ESPI), concentration profile measurements were carried out. A phase-shifting algorithm was also employed to give whole field measurements. Momentum transport in the velocity boundary layer was examined using Particle Image Velocimetry (PIV), which is also a non-intrusive optical technique. The two measurements were taken independently so as to reduce the effect that seed particles may have on the interferometric measurements. A concentration profile was developed above a surface by passing airflow across a flat plate containing a well of ethanol. The rate of mass transfer is obtained from the concentration profile produced as the ethanol vapour diffuses into the airflow. The experiment is set up to measure diffusion from a flat plate and to compare it with the integral solution of the mass transfer equation. Data is presented to show the dependence of the Sherwood number on the Reynolds number.

The effect of non-Fickian diffusion into surrounding rocks on contaminant transport in a fractured porous aquifer

“…Note that assuming the concentration C 1 on the rock-aquifer interface YZ0 to be equal to the mean concentration of solute in the aquifer, C, (boundary condition (2.11)) we slightly overestimate the value of concentration in the surrounding rocks. The boundary condition (2.11) is approximation of the more general mass transfer equation (Welty 2001): v a C 1 =vY a Z ShðC 1 K C Þ at YZ0, where the Sherwood number ShZ kh a =D 1 is greater than 10 for the regimes characterized by high Peclet numbers (owing to the high values of convective mass transfer coefficient k, which is much greater than the effective diffusivity of the rock matrix; Guo et al 1999;McGuire et al 2004).…”