Velocity open channel flow

Anderson, A.G. (1965). Influence of channel roughness on the aeration of high-velocity, open channel flow. 1 lAHR Congress Leningrad 1(37) 1-13. 

Hungr, O. and N. R. Morgenstern. 1984. Experiments in high velocity open channel flow of granular materials. G eotechnique 34, 405-413. 

In filters etc. the particles become largely static in a bed or cake and in such cases the fluid therefore passes through a fixed array of particles or a porous solid and experiences drag as it does so (Figure 2.9). The particles resist the flow, reduce the velocity and give rise to an enhanced pressure drop compared with that in open channel flow. 

Solids-liquid-gas mixing 275 Solids-liquid mixing 275 Solids—solids mixing 275 Sonic velocity 150, 156,158, 189 Sorel effect, thermal diffusion 589 Spalding, D. B, 393,562 Sparrow, E. M. 465, 564 Specific energy, open channel flow 98... 

In solving open channel flow equations, the THINC I code (Zernick et al., 1962) was the first calculational technique capable of satisfactorily assigning inlet flows to the assemblies within a semiopen core. In the THINC I approach, it was recognized that the total pressure distribution at the top of the core region is a function of inlet pressure, density, and velocity distributions. This functional dependence can be expressed as,... 

Taylor (T4, T6), in two other articles, used the dispersed plug-flow model for turbulent flow, and Aris s treatment also included this case. Taylor and Aris both conclude that an effective axial-dispersion coefficient Dzf can again be used and that this coefficient is now a function of the well known Fanning friction factor. Tichacek et al. (T8) also considered turbulent flow, and found that Dl was quite sensitive to variations in the velocity profile. Aris further used the method for dispersion in a two-phase system with transfer between phases (All), for dispersion in flow through a tube with stagnant pockets (AlO), and for flow with a pulsating velocity (A12). Hawthorn (H7) considered the temperature effect of viscosity on dispersion coefficients he found that they can be altered by a factor of two in laminar flow, but that there is little effect for fully developed turbulent flow. Elder (E4) has considered open-channel flow and diffusion of discrete particles. Bischoff and Levenspiel (B14) extended Aris s theory to include a linear rate process, and used the results to construct comprehensive correlations of dispersion coefficients. 

EXAMPLE 4.7 Measurements of the velocity profile in an open-channel flow (similitude in momentum transport)... 

You will be measuring velocity profiles in a fully developed open-channel flow (no change with longitudinal distance). To get an idea of which parameters you need to measure accurately, you need to perform an order-of-magnitude analysis on equation (4.26). 

What is turbulent flow We will use the simple illustration of a free-surface flow given in Figure 5.1 to describe the essential points of the turbulence phenomena. Turbulent open-channel flow can be described with a temporal mean velocity profile that reaches a steady value with turbulent eddies superimposed on it. These turbulent eddies are continually moving about in three dimensions, restricted only by the boundaries of the flow, such that they are eliminated from the temporal mean velocity profile, u in Figure 5.1. It is this temporal mean velocity profile that is normally sketched in turbulent flows. 

Figure 11 Schematic diagram of the experimental facility for simultaneous measurement of turbulent velocity field and free-surface wave amplitude in an open channel flow using PIV (Li et al., 2005c).

Figure 13 plots an example of the processed PIV frame. The turbulent velocity field and its boundaries, solid wall, and liquid-free surface are simultaneously shown in Figure 13. The turbulence structures such as the coherent vortical structure near the bottom wall and its modification after release from the no-slip boundary condition near the free surface of the open-channel flow, and the evolvement of the free-surface wave can be seen in Figure 13. This simultaneous measurement technique for free-surface level and velocity field of the liquid phase using PIV has been successfully applied to the investigation of wave-turbulence interaction of a low-speed plane liquid wall-jet flow (Li et al., 2005d), and the characteristics of a swirling flow of viscoelastic fluid with deformed free surface in a cylindrical container driven by the constantly rotating bottom wall (Li et al., 2006c).

In general, the velocity is not the same at every point in a cross section of pipe it is faster near the center than at the walls. (One may verify this for the analogous open-channel flow by dropping bits of wood or leaves on a flow of water in a ditch or gutter and noting that those in the center go faster than those at the side.) Therefore, to calculate the total flow in across the system boundaries at point 1, we break up the area across which the flow is entering... 

The pitot tube allows us to measure a liquid height (a very easy thing to measure) and to j calculate a velocity from it by Bernoulli s equation. The device, exactly as shown in Fig. 5,6, is used for finding velocities at various points in open-channel flow and for determining the velocities of boats. 

In problems involving changes in velocity and free surfaces, the Froude number plays a very important role, e.g., in ship-model studies and open-channel flow. We saw in Chap. 7 that it is the key parameter in describing hydraulic jumps. 

Velocity distribution and characteristics in unsteady open-channel flow over rough bed... 

Ma A.X. Lu Y. Lu Y.J. 2012. Advances in velocity distribution and bed-load transport in unsteady open-channel flow. Advances in Water Science 23 (1) 134-14. 

Song T. Graf W. H. 1996. Velocity and turbulence distribution in unsteady open-channel flows. Journal... 

Tu H. Graf W.H. 1992. Velocity distribution in unsteady open-channel flow over gravel beds. Journal of Hydroscience and Hydraulic Engineering 10(1) 11-25. 

Douma, J.H. (1943). Discussion of Open channel flow at high velocities, by L. Standish Hall. Trans. ASCE 0% 1462-1473. 

Dunham, H.F., Ewald, R.F. (1916). Discussion of The hydraulic jump in open channel flow at high velocity. Trans. ASCE 80 390-404. 

Hall, L.S. (1931). Improving the accuracy of instruments. Civil Engineering 1(12) 1098-1101. Hall,L.S. (1940). Silting of reservoirs. Journal American Water Works Association25-42. Hall,L.S. (1943). Open channel flow at high velocities. Trans. ASCE 108 1394-1434 1494-1513. Hall, L.S. (1947). The influence of air entrainment on flow in steep chutes. Proc. Hydraulics Conference. 298-314, J.W. Howe, J.S. McNown, eds. State University of Iowa Iowa. 

Anonymous (1952). KarlR. Kennison. Engineering News-Record 148(May 29) 68. P Anonymous (1964). Kennison, Karl R. Who s who in engineering 9 990. Lewis New York. Kennison, K.R. (1916). The hydrauHe jump in open-channel flow at high velocity. Trans. ASCE 80 338-420. 

Taylor, E.H. (1945). Discussion of Coefficients for velocity distribution in open-channel flow. Trans. ASCE 110 646-648. 

A semi-emperical turbulent one-equation model is developed for rectangular open channel flows of water and viscoelastic fluids. The model is used to predict friction factor vs. Reynolds number relations, velocity profiles, eddy viscosity distributions and turbulent energy budgets. Comparisons are made between the model and the measured results using a Laser Doppler Anemometer. 

The original 0.71-m interconnecting pipes and their bellows had permitted the hot pressurized feedstock to communicate by open channel flow over the outlet weir in the upstream reactors, through the bellows connection into the downstream reactors with a fixed difference in elevation of 0.178 m and at a velocity of less than 0.3 m/s through the nearly full pipes under full production flow. The adaptation (Fig. 42.4), however, doubled the head between R4 and R6 to 0.356 m. There was also a signiflcant weir waterfall (velocities from 1.8 to... 

In this chapter, some very important principles regarding water flows were introduced. Since water is the principal carrier of slurry mixtures, the tools developed in this chapter such as hydraulic friction gradients and methods to correlate the friction velocity with the friction factor will be extensively used for pipe flow and open channel flow of heterogeneous mixtures (Chapters 4 and 6). 

Initially, the work was done in the 1930s and 1940s on open channel flows and is discussed in Chapter 6, Section 6-2-3, The distribution of volumetric concentration is shown to be a function of depth of the liquid in an open channel flow, raised to a exponent. The exponent is a function of the relation of the terminal velocity to the friction velocity. 

On the analogy of hydraulic jump in open channel flow, the granular jump can occur in a horizontal pneumatic conveying, provided that for a given U the particle flow pattern belongs to the suspension flow accompanied with the settled layer and that the particles are introduced into the pipe with velocity hi er than the equilibrium particle velocity for U. Since the deceleration of particle is not observed in the upstream side of the jump, it is infared that the particle is discontinuously decelerated at the jump. 

A special design of the liquid distributor is installed to feed all spray stages in case of multi-stage LamRot. The bores are also inclined to the radial and axial direction and maintain quite equal flow to each stage. The alignment ensures for open channel flows within the whole liquid distributor. No regions of low flow velocity exist within the wheel [43]. 

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