Channel/medium

When a pure gas flows through a channel the accompanying fall in pressure is accounted for partly by acceleration of the flowing stream and partly by momentum transfer to the stationary walls. Since a porous medium may be regarded as an assembly of channels, similar considerations apply to flow through porous media, but in the diffusional situations of principal interest here accelerational pressure loss can usually be neglected. If more than one molecular species is present, we are also interested in the relative motions of the different species, so momentum transfers by collisions between different types of molecules are also important. 

A porous medium may be regarded as a complex assembly of interconnected channels and, if each of these is regarded as a capillary Cube, one is led to speculate that a flux relation of the algebraic form (2.5) might be appropriate v en all the channels have diameters much smaller chan the mean... 

Though by no means a complete theory, this is at least a reasonable explanation of the Knudsen minimum, and it then remains to explain why the minimum is not observed for flow through porous media. Pollard and Present attributed this to the limited length/diameter ratio of the channels in a typical porous medium and gave a plausible argument in favor of this view. 

Coreless furnaces derive their name from the fact that the coil encircles the metal charge but, in contrast to the channel inductor described later, the cod does not encircle a magnetic core. Figure 8 shows a cross section of a typical medium sized furnace. The cod provides support for the refractory that contains the metal being heated and, therefore, it must be designed to accept the mechanical loads as well as the conducted thermal power from the load. 

A typical m el ter iastalled in a medium sized brass foundry contains 4500 kg of brass and its inductor is rated 500 kilowatts. Brass is an alloy containing copper and zinc. Zinc vaporizes at temperatures weU below the melting temperature of the alloy. The channel iaductor furnace s low bath temperature and relatively cool melt surface result in low metal loss and reduced environmental concerns. Large dmm furnaces have found use in brass and copper continuous casting installations. 

When water is injected into a water-wet reservoir, oil is displaced ahead of the injected fluid. Injection water preferentially invades the small- and medium-sized flow channels or pores. As the water front passes, unrecovered oil is left in the form of spherical, uncoimected droplets in the center of pores or globules of oil extending through intercoimected rock pores. In both cases, the oil is completely surrounded by water and is immobile. There is htde oil production after injection water breakthrough at the production well (5). 

Sewage flows slowly downward over the filter medium and the effluent is coUected in vitrified tile underdrains which coUect the filter effluent and circulate air into the filter. The underdrains discharge into a main coUection channel which, in turn, discharges into the final settling tank. 

Medium-Energy Ion Scattering with Channeling and Blocking (MEIS)... 

Figure 7.12. Chronology of message capacity showing exponential increase with time. The number of voice channels transmitted per fibre increases rapidly with frequency of the signalling medium. The three right-hand side points refer to optical-fibre transmission (after MacChesney and DiGiovamti 1991, with added point).

When a dilute solution of a polymer (c << c ) is equilibrated with a porous medium, some polymer chains are partitioned to the pore channels. The partition coefficient K, defined as the ratio of the polymer concentration in the pore to the one in the exterior solution, decreases with increasing MW of the polymer (7). This size exclusion principle has been used successfully in SEC to characterize the MW distribution of polymer samples (8). 

Mixing Due to Obstructions The tortuosity of the flow channels in a porous medium means that fluid elements starting a given distance from each oilier and proceeding at the same velocity will not reniain tlie same distance apart. 

The object interacts with a flowing medium. Sails interact with the wind, rafts float downstream, a spacecraft is propelled by the stream of photons (light) from the sun. This is more of a channeling type of propulsion m that the propelled object deflects the flowing stream m such a way that it is forced to move in desired direction. 

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