On the measurement of strain rate in an oscillatory baffled column using particle image velocimetry

We report, for the first time, our direct experimental measurement of veloc ity vectors and strain-rate distributions in an oscillatory baffled column (OBC) using time-resolved particle image velocimetry (PIV). The technique a llowed a time series of spatial velocity maps to be obtained for several ph ases per oscillation cycle and the results, comprising several thousand suc h maps, illustrate in detail the variations of velocity and strain rate in a baffled region over a range of oscillation amplitudes and oscillation fre quencies and provide a deep insight into the mixing, vortex convection and transport mechanism in such a device. The results show that an OBC not only provides enhanced mixing, but also offers low strain rates, which are lowe r than those in stirred tank vessels. We have also reported for the first t ime the quantitative correlation between the strain rate and the power diss ipation in an OBC. Using the PIV technique we are able to quantify the stra in rates experienced in an OBC, (C) 2000 Elsevier Science Ltd. All rights r eserved.