Lateral Flow

One of the basic mechanisms in fluid loss prevention is shown in Figure 2-1. The fluid contains suspended particles. These particles move with the lateral flow out of the drill hole into the porous formation. The porous formation acts like a sieve for the suspended particles. The particles therefore will be captured near the surface and accumulated as a filter-cake. 

Lateral flow (L) within the soil layer containing plant roots is small for most landfill cover situations and is zero for lysimeters with sidewalls. During the course of a hydrologic year, ASW is usually small in comparison to the other terms, but it may be large on a daily basis. A primary focus for the design is PRK below the ET landfill cover as represented by the rearranged equation ... 

Development of the Environmental Policy Integrated Climate (EPIC) model and its predecessor, the Erosion Productivity Impact Calculator, began in the early 1980s.69 70 The first version of EPIC was intended to evaluate the effects of wind and water erosion on plant growth and food production. More recent versions also evaluate factors important to other environmental issues. EPIC is a onedimensional model however, it can estimate lateral flow in soil layers at depth. All versions of EPIC estimate surface runoff, PET, AET, soil-water storage, and PRK below the root zone—these complete the hydrologic water balance for an ET landfill cover. 

Overlain by a graded granular or synthetic filter to prevent clogging Allow lateral flow and discharge of liquids Low-permeability liner design FML component Thickness >20 mil... 

Dyed particles also are commonly used in diagnostic lateral flow tests (like the common home pregnancy test), as the colors can be seen with the eye without the need for special detectors. In this type of assay, antibodies or antigens are coupled to the dyed particles and a sample solution applied to the test strip carries them along within a membrane. The particles then are captured at points in the membrane that represent either a control or a positive sample result. Large numbers of color particles docking at these points within the membrane create the visual lines associated with these disposable tests. 

Inorganic particles are used extensively in various bioapplications, too. Gold nanoparticles long have been used as detection labels for immunohistochemical (IHC) staining and lateral flow diagnostic testing. These dark, dense particles provide single particle detection capability... 

As noted in Chapter 4, the term meridional overturning circulation, abbreviated MOC, is used to collectively describe all the water movements associated with the creation, lateral flows, and upwelling of the subsurfece water masses. 

Salinity occurs in coastal areas affected by seawater, in areas receiving salty water by lateral flow from salt-bearing rocks upstream, and also in otherwise non-saline environments as a result of soil waterlogging, mainly due to high ground water. In waterlogged land, whatever dissolved salt is brought in with the... 

U-bearing minerals and adsorption processes (Salah et al. 2000 Perez del Villar et al. 2000). The vertical and lateral flow of groundwater is responsible for the oxidation and dissolution of primary sulphides, leading to acidic solutions that facilitated the oxidation and dissolution of uraninite. The resulting uranyl cations migrated and precipitated as uranyl minerals, mainly phosphates, silicates, silico-phosphates. In certain local conditions, reduction of these uranyl cations allowed precipitation of coffinite with a high content of P and LREE. Adsorption of uranium, together with P, mainly occurs on Fe-oxyhydroxides, but this kind of uranium retention seems less efficient than the precipitation, at least in the close vicinity to the... 

Circulation and shear of the liquid in a vessel can be accomplished with external pumps and appropriate location of suction and discharge nozzles, but a satisfactory combination of vertical and lateral flows is obtained more economically by internal impellers, baffles, and draft tubes. Some general statements about dimensions, proportions, and internals of a liquid mixing vessel can be made. 

Since the rise or fall of liquid droplets is interfered with by lateral flow of the liquid, the diameter of the drum should be made large enough to minimize this adverse effect. A rule based on the Reynolds number of the phase through which the movement of the liquid drops occurs is proposed by Hooper and Jacobs (1979). The Reynolds number is Dhup/fi, where Dh is the hydraulic diameter and u is the linear velocity of the continuous phase. The rules are ... 

The most useful impellers are ihe simple flat paddle, the marine-type propeller, and the turbine, If any of these are on a vertical shaft rotating on the center line of a cylindrical vessel, the fluid motion will be one of rotation. A vortex forms around which the liquid swirls. A minimum of turbulence and of vertical and lateral flow motion will result, very little power can be applied. 

In the discussion of concentration polarization to this point, the assumption is made that the volume flux through the membrane is large, so the concentration on the permeate side of the membrane is determined by the ratio of the component fluxes. This assumption is almost always true for liquid separation processes, such as ultrafiltration or reverse osmosis, but must be modified in a few gas separation and pervaporation processes. In these processes, a lateral flow of gas is sometimes used to change the composition of the gas on the permeate side of the membrane. Figure 4.14 illustrates a laboratory gas permeation experiment using this effect. As the pressurized feed gas mixture is passed over the membrane surface, certain components permeate the membrane. On the permeate side of the membrane, a lateral flow of helium or other inert gas sweeps the permeate from the membrane surface. In the absence of the sweep gas, the composition of the gas mixture on the permeate side of the membrane is determined by the flow of components from the feed. If a large flow of sweep gas is used, the partial... 

Because of their low pressure drop, structured reactors in practice dominate the field for treating tail gases. Figure 2 presents the major types of reactor. The monolithic reactor represents the class of real structured catalytic reactors, whereas the parallel-passage reactor and the lateral-flow reactor are based on a structured arrangement of packings with normal catalyst particles. 

Bead-string reactors have the advantages of lateral-flow reactors but not the disadvantage of the low mass transfer rates in the units of the lateral-flow reactors. 

Sie ST, Calis HP. Parallel passage and lateral-flow reactors. In Cybulski A, Moulijn JA, eds. Structured Catalysts and Reactors. New York Marcel Dekker, 1998 323-354. 

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