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In this work, the fluid flow and mass transfer due to the presence of an electric field in a rectangular channel is examined. We consider a mixture of water or another neutral solvent and a salt compound, such as sodium chloride, for which the ionic species are entirely dissociated. Results are produced for the case in which the channel height is much greater than the electric double layer (EDL) (microchannel) and for the case in which the channel height is of the order of the width of the EDL (nanochannel). Both symmetric and nonsymmetric velocity, potential, and mole fraction distributions are considered, unlike previous work on this problem. At small electrolyte concentrations, the Debeye-Huckel picture of the electric double layer is recovered; at larger concentrations, the Gouy-Chapman picture of the electric double emerges naturally. The numerical results presented here agree with analytical solutions of a singular perturbation analysis, which is valid as the channel height increases. In the symmetric case for the electroosmotic flow so induced, the velocity field and the potential are similar. In the asymmetric case corresponding to different wall potentials, the velocity and potential can be vastly different. The fluid is assumed to behave as a continuum, and the volume flow rate is observed to vary linearly with channel height for electrically driven flow, in contrast to pressure-driven flow, which varies as height cubed. This means that very large pressure drops are required to drive flows in small channels. However, useful volume flow rates may be obtained at a very low driving voltage.

The deep currents in the Northwest Pacific Basin reveal that the currents enter from south in a northward direction along the western boundary at a longitude of 148 degrees E and in the deep passage near a longitude of 170 degrees E, and from the north in the Kamchatka Current.

A dynamically consistent method of locating the rough wall origin y(sub 0) is presented that is applicable to large- and small-scale rib roughness elements, where scale is defined relative to the depth of flow. Using the results of Reynolds-averaged computational fluid dynamics (CFD) calculations, a near-standard resistance law is derived in which k(sub s), the equivalent sand roughness parameter, for large-scale roughness is flow-depth dependent. It is postulated that the relationship with depth of both y(sub 0) and k(sub s), when scaled appropriately, is independent of rib roughness height and spacing. For k(sub s) this is supported by the CFD results.

The flow around two in-line surface-mounted cubes in a thin laminar boundary layer was experimentally investigated as a function of obstacle spacing for a Reynolds number of 22,000 based on approach velocity and cube height. Mean velocity measurements with Laser Doppler Velocimetry and surface flow patterns, obtained with an oil film technique, show that three distinct mean flow field structures exist based on obstacle spacing. Frequency spectra of velocity and surface pressure fluctuations reveal that these structures are related to three regimes of wake flow periodicity. For small spacings, the shear layer separating from the first cube reattaches on the sides of the second obstacle and wake periodicity can only be detected in the wake of the downstream cube. For a critical spacing range, the fluctuations in the gap and wake lock-in. For larger spacings, a second horseshoe vortex appears at the windward base of the second cube. Observations using dye-injection and smoke-wire techniques are consistent with these results.

The review documents new developments in electron spin resonance (ESR) instrumentation and techniques. Discussion on the two-dimensional Fourier tansform ESR for determining molecular dynamics in complex fluids, pulsed ESR for large intramolecular distances, and ESR technique extension to high magnetic fields for optical measurement of molecular motions is presented.

This paper reports laser-Doppler anemometer measurements of mean velocity and turbulence statistics upstream and downstream of a 3-mm forward facing step in a shallow open channel flow. The Reynolds numbers based on the momentum thickness ([Theta]) of the approaching upstream flow and step height (h) are in the range 1010 [is less than or equal to] [Re.sub.[Theta]] 2240 and 960 [is less than or equal to] [Re.sub.h] [is less than or equal to] 1890, respectively. Measurements are obtained at 50 step heights upstream of the leading edge of the step and 1 [is less than or equal to] x/h [is less than or equal to] 162 downstream of the step. The results show that the overlap region develops more slowly than the inner and outer regions. The mean field recovers at x/h = 50. Distributions of the turbulence intensity tend to become self-similar for x/h> 100 but the profiles do not necessarily collapse onto the upstream profiles. [DOI: 10.1115/1.1383971]

Measurements of the flow field were made of the axisymmetric flow in a differentially heated rotating fluid annulus by using a long-term tracking of a tracer particle. Its meridional flow profile is composed of a flow circulating in a large direct (Hadley) cell, which consists of thin boundary and top horizontal layers, and another one in the interior of that cell. Our measurements show that little mixing of the flow between the Hadley cell and the interior occurs and two secondary cells exist in the interior. These cells cause a trajectory of the tracer particle to be chaotic, where the particle follows the main cyclic route but is occasionally trapped in the secondary cells for indefinite times. Very close to the transition to the wave regime, a mixed structure appears consisting of both the axisymmetric and the wave flows in the meridional flow field: an unsteady wave flow occurs in the interior of the Hadley cell.