Showing papers by "Adrian Wing-Keung Law published in 2008"
TL;DR: In this paper, the authors developed a mathematical model on the cumulative effects due to brine discharges into shallow coastal waters with a flat seabed, which incorporates the effects of tidal currents, which are commonly encountered in the natural coastal environment.
15 citations
TL;DR: In this paper, the critical flux of a model fouant was investigated in reverse osmosis and the potential benefit of using AC field gradients to do this was illustrated for a model foulant.
15 citations
TL;DR: In this article, an experimental study on starting square jets at Reynolds numbers ranged from 2000 to 5000 (based on the jet diameter and the bulk mean velocity on jet exit plane) using planar laser induced fluorescence for flow visualization and particle image velocimetry for velocity measurements, respectively.
Abstract: This paper presents results of an experimental study on starting square jets at Reynolds numbers ranged from 2000 to 5000 (based on the jet diameter and the bulk mean velocity on the jet exit plane) using planar laser induced fluorescence for flow visualization and particle image velocimetry for velocity measurements, respectively. Similar to starting a circular jet at Reynolds numbers below 3000, vortex leapfrogging was found to appear, whereas pinch-off for the leading vortex ring was observed at higher Reynolds numbers. The "imperfect" leapfrogging between the third and the fourth vortex rings promoted growth of instability, which had led to the transition to turbulence for the entire jet. The maximum circulation that a vortex ring can attain during its formation is reached at the nondimensional time (t* = tW 0 /D e ) within the range of 1.6 to 2.4. The pinch-off of the leading vortex ring appeared shortly after the jet initiation for Reynolds numbers above 3000. Axis switching was found to play an important role for the vortex development in starting square jets. The interaction between the axis-switched vortex ring and the square-shaped jet stem facilitated the generation of contrarotating streamwise vortices at the corners of the jet stem. They were actually rotating in the opposite sense as those responsible for axis switching, and their existence had facilitated the thinning of the jet stem, causing a fast pinch-off for the leading vortex ring.
11 citations
TL;DR: In this paper, the authors investigated the gravity-driven starting jet characteristics over the range of Reynolds numbers from 1179 to 10 611 using planar laser induced fluorescence and particle image velocimetry.
Abstract: The gravity-driven starting jet characteristics over the range of Reynolds numbers from 1179 to 10 611 have been investigated using planar laser induced fluorescence and particle image velocimetry. Of the 17 cases investigated, pinch off for the leading vortex was found to appear at Reynolds number above 3000. For those cases involving pinch off, limiting values for the nondimensional circulation for the leading vortex could be identified at around 1.26 and the nondimensional energy was at about 0.35±0.01, respectively. The former agrees with the universal value proposed by Shusser et al. [Phys. Fluids 18, 033601 (2006)] to within 9%, while the latter lies within the analytical result range (from 0.27 to 0.4) proposed by Gharib et al. [J. Fluid Mech. 360, 121 (1998)]. The results thus suggested that the pinched-off vortex ring would achieve similar characteristics and that may also be independent of the generation mechanism.
10 citations