Acoustic observations of suspended participate matter in the ocean
CLOUDS of suspended particulate matter in the ocean have been observed by satellite1, sensed by nephelometers2, and sampled by water bottles. We present here evidence that it may be possible to observe oceanic suspended particulate matter acoustically. The particulate matter discussed is thought to have arisen from a dredging operation. It is also thought that the suspended matter is present at lower concentrations than any in any other case recorded acoustically3. Certain questions, as yet unresolved, regarding acoustic scattering strengths are also discussed.
Dispersion of Particulates in the Ocean Studied Acoustically: The Importance of Gradient Surfaces in the Ocean
Knowledge of the rate of dispersion of particulate matter dumped in the upper ocean and of the processes governing that dispersion is fundamental to an understanding of the effects of dumping on the ocean environment. Accurate chemical dilution rates of dumped material cannot be determined without a knowledge of the spacial distribution of ocean dumped material and the way in which that distribution changes with time. Acoustical methods offer one approach to studying ocean dispersion of dumped material. Acoustical results presented herein show some of the complicated effects which gradients in oceanic parameters, such as temperature and density, produce in the dispersion of particulate matter dumped in the ocean.
Effect of superficial gas velocity on the particle temperature distribution in a fluidized bed with heat production
The heat transfer behavior of particles and gas in an olefin polymerization fluidized bed was numerically analyzed using an in-house developed 3-D computational fluid dynamics discrete element model (CFD-DEM). First the implementation of the model was verified by comparing simulation results with analytical results. A constant volumetric heat production rate was implemented in the particle energy equation to mimic the heat production due to the polymerization reaction. It was found that the probability density function (PDF) of the particle temperature becomes more homogeneous with increasing superficial gas velocity. Furthermore, instantaneous snapshots of the thermal driving force (the difference between the single particle temperature and bed-average gas temperature, Tp− ) for different heat production rates provide detailed insight in the particle temperature distribution inside the fluidized bed. The time- and bed-averaged particle convective heat transfer coefficient, which was calculated by Gunn׳s correlation, was found to be independent of the superficial gas velocity. This is explained by the fact that the relative velocity of gas and particles in the emulsion phase, where most of the particles and gas interact, is hardly influenced when increasing the gas superficial velocity. From the spatial distribution of Nusselt number, it becomes apparent that the high heat transfer regions are found in the wake of rising bubbles, whereas low heat transfer rates are found in the clouds of the bubbles.