Sources of Flow

There must be a driving force to make flow occur otherwise all flow would be brought to a halt by viscous forces. The driving force is different in different kinds of systems. For example, in gas chromatography an outside source of pressure, such as a tank of pressurized gas, forces the gas phase through the column. Pumps are most often used in liquid chromatography, field-flow fractionation, ultraflltration, and so on, because of the precise 

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Successful operation of the viscometer depends on good control of possible sources of flow variations in the system which include pump pulsations, temperature variations and restrictions in the GPC columns and fractional sections of tubing. 

Essentially the only source of flow in a solid ion-exchange membrane (ion-exchanger) is electro-osmosis. This is a flow induced by the interaction of the electric field with the space charge distributed in the fluid present in the solid. In this respect, electro-osmosis may be regarded as a relative of electro-convection in a hydrodynamically free solution. 

Baseflow the continual contribution of groundwater to rivers and is an important source of flow between rainstorms. 

Broecker, W. S., T. Takahashi, H. J. Simpson and T. -H. Peng (1985) Sources of flow patterns of deep ocean waters as deduced from potential temperatme, salinity and initial phosphate concentration. J. Geophys. Res. 90, 6925-39. 

Using a continuum rather than cellular model implies that the growing foam is regarded as a fluid with a continuously distributed source of flow. Hence, the flow rate is also a function of position the (hydrodynamic) pressure gradient is resulted from inertia, gravity and stress mechanisms operating in the fluid. 

The peak variance is measured in volume units. This equation also assumes that there are no additioiuil sources of flow that would dilute the sample. An altenutive way to write this equation is as follows ... 

The flow of the coolant around components and structures can cause structural vibrations due to the unsteady characteristics of the gas motion. The turbulence and the vortex shedding from an object protruding into the flow are the main sources of flow-induced vibrations that are considered. Flow-induced vibration analysis is done in two steps 1) determination of... 

For a given number of independently working components in a network with merging flows, the maximum amount of transmitted flow is associated with a network topology where each component failure is associated with choking a single source of flow and the number of sources of flow is maximal. 

The presence of EOF as the source of flow of the electrolyte through the CEC column has two very profound effects. First, by the nature of the EOF, the pressure difference across the whole CEC column bed is zero. This means that much smaller particle sizes can be used, down to 1 pm particle diameter, with 3-5 pm particles being used routinely. Second, the plug-like profile of the EOF is responsible for the typical higher separation efficiencies achieved in CEC compared to LC. 

The main causes of reduced output are increased flow restriction, commonly a result of clogged screens and screw wear. As screens perform their function properly and capture contaminants in the melt stream, they create an increased restriction to flow through the system. This increased restriction will result in higher head pressure. Additionally, there will be more recirculation of melt in the screw channel and less throughput. As discussed above in the section on high melt temperature, changing the screens should alleviate this problem. It is possible that other sources of flow restriction could exist, such as screens with an incorrect mesh size or a valve in the extruder head. 

For a hydroelectric power plant to produce a steady flow of electricity, a steady source of water must flow into the reservoir. To ensure this, some hydroelectric power plants have an upper reservoir and a lower reservoir. Water from the upper reservoir is used to produce electricity and then channeled into a lower reservoir, rather than back into the river downstream of the dam. During off-peak hours, water from the lower reservoir is pumped back up to the upper reservoir to be used again as a source of flowing fluid for the turbines. In the absence of a lower reservoir, water is directed into the river downstream of the dam. 

Energy source this can either be a source of flow or a source of effort for example, pressure imposed on the mouthpiece of a clarinet, or gravity acting on a falling apple... 

Section 6.1 begins with a description of mechanisms/ driving forces/sources that cause bulk flow to take place in the separation device. Following a brief description of these sources of flow into and out of the separation device, as well as inside the device, we provide a brief illustration of a variety of ways in which the feed is introduced into the separator. Section 6.2 will identify the general equations of change in an open separator. 

The simplest section to model can be treated as three sources of flow drag flow due to the relative motion of the screw and barrel pressure back-flow along the channel, as a result of the pressure build up along the channel, often approximated as linear from feed throat to the tip of the screw leakage flow over the flight tips, again as a result of the positive pressure gradient. 

For continuously extruded products, such as sheet and profile extrusions, thickness uniformity is a key quality factor, and it is directly linked to flow oscillations or flow disturbances at the die. Many sources of flow oscillations in the extrusion system are identified, and methods are shown on how to configure the melt delivery system to minimize their transmission to the die. These methods are illustrated with a model based on the theory of hydraulic transients. 

Thickness uniformity is a major concern for many continuously extruded products, such as sheet and profile extrusions. Any flow oscillation or disturbance at the die will manifest itself in a comparable thickness variation in the product. Therefore, diagnosing and eliminating flow disturbances in the melt delivery system is key to good thickness uniformity. This first involves identifying the sources of flow disturbances so that they may be eliminated or minimized. Secondly, a method is shown on how to design the delivery system to minimize the transmission of flow disturbances to the product. 

The polymer can be a source of flow instability, which will depend on the stability of the extruder and the screw design. A screw not suited to the polymer will not equate the inherent flow rates of solids conveying, melting, and metering. The take up and release of material between the three stages of the extruder process to accommodate... 

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