Most of the current ash transport and dispersion models neglect particle-fluid (two-way) and particle-fluid plus particle-particle (four-way) reciprocal interactions during particle fallout from volcanic plumes. These interactions, a function of particle concentration in the plume, could play an important role, explaining, for example, discrepancies between observed and modelled ash deposits. A...

The settling dynamics of spherical and elliptical particles in a viscous Newtonian fluid are investigated numerically using a finite difference technique. The terminal velocity for spherical particles is calculated for different system sizes and the extrapolated value for an infinite system size is compared to the Oseen approximation. Special attention is given to the settling and tumbling moti...

We study the settling dynamics of non-Brownian prolate spheroids under steady-state sedimentation. We consider the case of moderate particle Reynolds numbers properly taking into account the hydrodynamic effects. For small volume fractions, we find an orientational transition of the spheroids, characterized by enhanced density fluctuations. Around the transition, the average settling velocity h...

Design of primary settling tank has historically been done more empirically than rationally. The main reason for this is a lack of understanding of what pollutants primary settling tank are capable of removing. Inlets should be designed to dissipate the kinetic energy or velocity head of the mixed liquor. They should be able to distribute the flow equally in vertical and horizontal directions. ...

Sedimentation of red blood cell aggregates was experimentally investigated by optical imaging. Suspensions of red blood cell at low hematocrit were obtained from blood of healthy donors. The velocity of three-dimensional red blood cell aggregates was measured using particle image velocimetry. The magnitude and spatial correlation functions of the velocity fluctuations of the settling aggregates...

a study was performed in hybrid up flow anaerobic sludge blanket (huasb) and anaerobic filter (af) reactors to compare the start-up time and optimum hrt required for the treatment of poultry slaughterhouse wastewater under similar loading conditions. initially, the reactors were started at an olr of 0.77 kg cod/m3.d and hrt of 36 h. loading rates were increased by reducing hrt 24, 16, 12, 10 an...

a r t i c l e i n f o Keywords: Marine snow Aggregates Biogeochemistry Density gradients Density interfaces Fluid dynamics Marine snow aggregates are often a dominant component of carbon flux and are sites of high bacterial activity; thus, small-scale changes in the settling behavior of marine snow can affect the vertical locations of carbon export and remineralization in the surface ocean. In ...

Methods for sizing single chamber tanks to remove different amounts of total suspended solids (TSS) have been available for some time. One method found in the literature uses the concept of upflow velocity (v) or the critical settling velocity of a particle in a tank to determine what size particles will be removed in the tank. The critical settling velocity depends on the relationship between ...