Water through pore, effect

K( results predict that flushing only a few pore volumes of clean water through the aquifer can displace the contamination, suggesting pump-and-treat remediation will be quick and effective. Models constructed with the surface complexation model, in contrast, depict pump-and-treat as a considerably slower and less effective remedy. 

Air flow is a measure of the resistance that a foam presents to air passing through it. Intuitively one would expect that large pore size presents less of an impediment to flow than small cells. This is indeed true and it is this method that quantifies the effect. It is obvious by now that air flow is an important property in the context of this book. Unfortunately, the ASTM tests were designed for the measurement of resistance to air flow only. Our interests focus on the flow of other fluids, specifically water, through the foam. Nevertheless, air flow represents a quick and precise way to determine the quahty of a foam. If you are not sure of the difference between a reticulated foam and an open-cell foam, this test will differentiate them. Reticulated foams offer much less resistance to flow than open-cell foams. 

The flow rate of water through the porous medium per unit total (bulk) area perpendicular to the direction of flow, the so-called specific discharge q, is related to the effective mean flow velocity in the pores along the x-axis, u, by... 

Water is stored in rocks mainly in pores. The effective porosity of a rock is the volume percentage of the rock that may contain water in pores. The values (Table 2.1) are high for nonconsolidated granular rocks—soils, clays, silts, and gravels. The porosity is low for crystallized rocks such as limestone, dolomite, and most igneous rocks. Movement of water through... 

Low-temperature calorimetry (S83,B112) has been used to study coarse porosity. The method is based on the fact that water in pores freezes at a lower temperature than water in bulk. The ice forms through the advance of a front, analogous to the intrusion of mercury or the desorption of water. Hysteresis effects indicated the existence of necks in the pores, and the occurrence of up to three distinct peaks on curves of apparent heat capacity against temperature was interpreted as indicating maxima in the pore size distribution. Coarsening of the pore structure on drying was confirmed. 

Effect of Flow Velocity. The flow velocity determines the shear rate and the pressure gradient. Therefore, the magnitude of a viscous force acting on a water droplet is directly related to flow velocity. This viscous force determines whether droplets can pass through pore throats smaller than themselves. It is also a factor in breakup of droplets into smaller droplets. 

One could assume that small organic ions are absorbed through water-filled pores or channels in the membrane, but the effective diameter of such pores means that large dmg ions would be excluded from this route. Although membranes are impermeable to large organic ions, nevertheless ion-pairing... 

Figure 11 Pulsatile drug-release patterns negligible release at early time points, followed by rapid and complete release after a predetermined lag phase. Exemplarily, a polymer-coated pellet is Ulustrated The intact macromolecular membrane effectively hinders drug release until the steadily increasing hydrostatic pressure within the pellet core (caused by the influx of water) induces crack formation, resulting in rapid drug release through water-filled pores/chaimels.

In middle-phase microemulsion, owing to the lowest ITT, oil and water can be solubilized in each other, and oil droplets can flow more easily through pore throats. The oil droplets move forward and merge with the oil downstream to form an oil bank. Because of the solubilization effect, water and oil volumes are expanded, leading to higher relative permeabilities and lower residual saturations. However, when kj increases faster than k with decreasing IFT, the oil saturation in the oil bank and the oil recovery rate are deterioated, if no viscosity alteration is made. 

In alkaline-polymer flooding, in addition to the polymer mobihty control effect, the precipitation (e.g., Ca(OH)2 and Mg(OH)2) caused by alkah also helps to increase sweep efficiency. Precipitates formed by alkalis may be able to flow through pores without blocking any flow, or reduce both oil and water permeabilities. However, precipitates combined with polymer can effectively reduce water permeability because polymer is in the water phase. 

Effect of Size of Water Molecule on Solvent Transport through Pore... 

A number of assumptions were made and then verified to develop a model (i) The rate-limiting step for transport is drug diffusion through pores (other steps such as water penetration into the matrix and drug dissolution occur in less than 40 hours), (ii) The effect of concentration dependence on the drug diffusion coefficient is not significant. This was verified by an analysis of diffusion effects at the concentrations in the... 

Viscous flow of water through a porous membrane will affect the unidirectional fluxes to small polar solutes as well as tracer water passing through these pores. For example, the unidirectional fluxes of small polar solutes or tracer water in the same direction as bulk water flow will be enhanced while that in the opposite direction will he hindered. Solvent drag refers to the effect of bulk water movement on the unidirectional fluxes of either tracer, water or small polar solutes. The term (1 — a)C J in Eqn. 10 represents the component of the overall unidirectional flux of the solute which is due to solvent drag (it is positive when and J are in the same direction and negative otherwise). 

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