A study of ̄ow visualization and residence time distribution is provided in order to model the ̄ow between two electrodes in a commercial ®lter-press reactor, the ElectroSynCell from Electrocell AB. Flow visualization indicates that both axial and lateral dispersion phenomena occur and a global plug ̄ow behaviour is observed. The ̄ow distribution is asymmetric due to the design of the inlet system ...

Dry powder inhaler (DPI) is a dosage form for delivering fi ne drug powders to the respiratory tract. Particle size and size distribution, proportion of fi nes, particle shape, particle surface roughness, fl ow rate and adhesion force have been reported to affect the aerosolization process. Several mechanisms for particle dispersion in DPI have been considered; a proposed mechanism to explain t...

We study the scale up problem for ow in porous media. The general nature of this problem is outlined, leading to a discussion of assumptions on random elds appropriate for the description of geological heterogeneities. The main point of this paper is to use direct numerical simulation to evaluate the ensemble averages describing uid dispersion, for ow in porous media. The relation between ensem...

Accurate estimate of longitudinal dispersion coe cient is essential in many hydraulic and environmental problems such as intake designs, modeling ow in esturies and risk assessment of injection of hazardous pollutants into river ows. Recent research works show that in the absence of knowledge about explicit relationships concerning longitudinal dispersion coe cient and its in uencing parameters...

The vortex ow which follows intense sound propagating in a bubbly liquid, is considered. The reasons for acoustic streaming are both nonlinearity and dispersion. That makes streaming especial as compared with that in a Newtonian uid. Conclusions concern the vortex ow induced in a half-space by initially harmonic or impulse Gaussian beam. The vortex ow recalls a turbulent ow with increasing in t...

Fractional advection–dispersion equations are used in groundwater hydrology to model the transport of passive tracers carried by uid ow in a porous medium. In this paper we develop practical numerical methods to solve one dimensional fractional advection–dispersion equations with variable coe1cients on a 2nite domain. The practical application of these results is illustrated by modeling a radia...

242 A dispersion are considered to be the dominant mechanisms of solute transport in the vadose zone, i.e., the variably saturated layer of soils and sediments between the soil surface and groundwater table (Jury and Flühler, 1992). Advection is associated with the average water fl ux or velocity, whereas hydrodynamic dispersion is modeled using an analog of Fick’s law corresponding to the Brow...

We investigate the longitudinal dispersion of passive tracers in a transversely bounded shear ow. The ow is assumed to be temporally irregular, but to possess smooth large scale spatial structure without signiicant small spatial scale motions. We show that, the existence of a region where the longitudinal velocity goes to zero linearly with 1 distance from the wall causes the tracers to \stick"...

Many diseases are related to cerebrospinal .uid (CSF) hydrodynamics. Therefore, understanding the hydrodynamics of CSF .ow and intracranial pressure is helpful for obtaining deeper knowledge of pathological processes and providing better treatments. Furthermore, engineering a reliable computational method is promising approach for fabricating in vitro models which is essential for inventing gen...

In this paper we discuss the formulation of the governing equations that describe ow of uids in porous media Various types of uid ow ranging from single phase ow to compositional ow are considered It is shown that all the di erential equations governing these types of ow can be e ectively rewritten in a fractional ow formulation i e in terms of a global pressure and saturation or saturations an...