For open channel

Gup and Vane Anemometers. A number of flow meter designs use a rotating element kept in motion by the kinetic energy of the flowing stream such that the speed is a measure of fluid velocity. In general, these meters, if used to measure wind velocity, are called anemometers if used for open-channel Hquids, current meters and if used for closed pipes, turbine flow meters. 

Current Meters. Various vane designs have been adapted for open-channel flow measurement. The rotating element is partially immersed and rotates rather like a water wheel. Operation is similar to that of vane anemometers. 

The most often used friction correlation for open channel flows is due to Manning (Trans. Inst. Civ. Engrs. Ireland, 20, 161 [1891]) and is equivalent to... 

In contrast, Tamburrino and Gulliver (2002) related liquid film coefficient from Gulliver and Halverson (1989) and Lau (1975) to their measurements of Hanratty s P for open-channel flows in a flume. They could not get a A l relationship. Instead, their result was the following ... 

One of the best and most widely used formulas for open-channel flow is that of Robert Manning, who published it in 1890. Manning found from many tests that the value of C varied approximately as Ry< and others observed that the proportionality factor was very close to the reciprocal of n, the coefficient of roughness in the classical Kutter formula. The Kutter formula, which was for many years the most widely used of all open-channel formulas, is now of interest principally for its historical value and as an outstanding example of empirical hydraulics. This formula, which may be found in several handbooks, included terms to make C a function of S, based on some river flow data that were later proved to be in error. This led to the Manning formula, which has since spread to all parts of the world. In metric units, the Manning formula is... 

In the case of a real liquid in an open channel, it is necessary to differentiate between the behavior at subcritical and supercritical velocities. Subcritical flow in a rectangular channel has been investigated experimentally and has been found to conform fairly well to ideal conditions, especially within the first part of the bend [44], As the flow continues around the bend, the velocity distribution becomes complicated by the phenomenon of spiral flow, which for open channels is analogous to the secondary counterrotating currents found at bends in closed pipes. 

Dutta, D., Leighton, D.T., Jr., Dispersion in large aspect ratio microchannels for open-channel liquid chromatography. Anal. Chem. 2003, 75, 57-70. 

In bound-state calculations, the Rayleigh-Ritz or Schrodinger variational principle provides both an upper bound to an exact energy and a stationary property that determines free parameters in the wave function. In scattering theory, the energy is specified in advance. Variational principles are used to determine the wave function but do not generally provide variational bounds. A variational functional is made stationary by choice of variational parameters, but the sign of the residual error is not determined. Because there is no well-defined bounded quantity, there is no simple absolute standard of comparison between different variational trial functions. The present discussion will develop a stationary estimate of the multichannel A -matrix. Because this matrix is real and symmetric for open channels, it provides the most... 

This formula expresses the surface integral obtained by integrating the kinetic energy integral by parts for open-channel orbital functions of the specified asymptotic form. In matrix notation,... 

Flow meters fall into the broad category of meters for open-channel flow measurements and meters for closed-channel flow measurements. Venturi meters are closed-channel flow measuring devices, whereas weirs and critical-flow flumes are open-channel flow measuring devices. 

Lincosamide antibiotics can prodnce nenromnscnlar block postjnnctionaUy by interacting with the open state of the acetylchohne receptor-channel complex. Lipophihcity, rather than stereochemistry of the mole-cnle, is important for open-channel blockade affecting primarily the off rate of channel blocking (15). Nenromnscnlar blockade after chndamycin has been reported (16). 

A simple sequential model for open channel block of the general type first proposed by Adams (52) provides a good first fit to the (+)-TC data ... 

Initially modeled as flow between infinite plates, Giddings et al. [36] showed that the performance of rectangular geometry for open channel LC columns... 

The pitot tube shown in Fig. 5.6 is suitable for open-channel flow but not for flow of the atmosphere or flow in pipes. For the latter two it is combined with a second tube, called a static tube shown in Fig. 5,7. Here some kind of pressure-differerice-measuring device is used to indicate the difference between the pressures of the pitot and static tubes. The pressure at point 2 is given by Eq. 5.23. By arguments similar to those used with the pitot tube it can be shown that the pressure difference between point 2 and the inlet of the pressure-difference meter, due to the weight of fluid in the tube connecting them, is exactly [balanced by the pressure difference due to gravity from point 1 to the other side of the meter, and hence that the pressure-difference meter... 

Crabtree (2009) detailed most of the flow meters used in industrial plants. His classification for selecting measuring technology with respect to process application is reproduced in Table 6.3. All flow meters are suitable for clean liquids except for the Ultrasonic-Doppler instrument and only electromagnetic instruments are unsuitable for low conductivity fluids. Most instruments are suitable for high temperature operation or application under certain conditions except for the ultrasonic instruments. Many flow meters are suitable for gases. Few instruments can be used for open channel flow or pipes that are semifllled with the exception of weirs and flumes. 

Robinson, A.R., Chamberlain, A.R. (1960). Trapezoidal flumes for open-channel flow measurement. Trans. American Society of Agricultural Engineers 3(2) 120-124. 

The molecular imprinting technique was also introduced into the microfluidic device for open-channel electrochromatographic enantiose-paration of chiral compounds [21]. In this approach, a layer of molecularly imprinted polymer (MIP) membrane was in situ chemically polymerized on the capillary wall using acrylamide as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. The thickness of MIP film could be controlled rather... 

For open channel flows, Sellin (7,8), Forester (9), and Petersen (10) investigated the polymer effect and obtained discharge capacity increase in the range of 40 - 50%. 

For the turbulent intensity of a drag reducing fluid in closed ducts, a few experimental results are available (4, 16, 23, 26). For open channel flows, only Newtonian intensity results have been reported (24,25). 

For open channel flows, as mentioned, no non-Newtonian results are available. Nakagawa, et al, (24) showed that the peak intensity of water in a rectangular open channel has a value of about 2.7 in terms of... 

The turbulent energy budgets were calculated for open channel flows... 

Fr Modified Froude number for open channel flow V /[g L (S - 1)] ... 

For open channels and partly filled ducts in turbulent flow, the equivalent diameter and Eq. (2.10-6) are also used (PI). For a rectangle with depth of liquid y and width b. 

The matrices Jir) and Nir) are diagonal matrices with elements for open channels given by [15]... 

Froude Number Dimensionless number for open-channel flow, defined as the ratio of the velocily to the square root of the product of the hydraulic depth and the gravitational acceleration. The Froude number equals 1 for critical flow. 

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