Sink point

The point sink can approximate airflow near a hood with round or square/rectangular shape. The point sink will draw air equally from all directions (Fig. 7.83). The radial velocity (mys) at a distance r (m) from the sink can be calculated as a volume rate of exhaust airflow q (mVs) divided by the surface area of an imaginary sphere of radius r ... 

Equations for the inflow velocity v and the corresponding capture distance (r, ) are listed in Table 7.23 for the most common point sink locations. 

TABLE 7.23 Inflow Velocity and Capture Distance for Some Common Locations of a Point Sink... 

FIGURE 7.85 Centerline velocity, V, and decay in the flow created by exhausts with finite dimensions and point sinks. /, round free-standing pipe 2, round opening in a infinite surface 3, unrestricted point sink, V q/Tifi-,4 point sink in an infinite surface, V = 2q /... 

The analytical solution for an infinitely flanged slot can be obtained by assuming that the inlet is composed of elemental point sinks.The velocity field of an infinitely flanged slot can be obtained by assuming the velocity to be uniformly distributed across the opening. The contribution to the velocity potential at point (x, y) due to the elemental line sink of length and located at (0, Q is given by... 

Point Sink A point sink is defined as a pcjint in space at which the fluid is continuously and uniformly drawn off. The radial velocity into the sink at a distance r from the sink is, in spherical coordinates,... 

The potential (Eq. 10.24) and stream (Eq. 10.25) functions for the point sink provide a simple theoretical representation of the velocity variations near real suction openings. Close to the origin the velocity for the point sink approaches infinity and deviates considerably from the actual fluid velocities. However, at distances greater than approximately one diameter from the finite opening, the velocities given by the sink model are reasonable approximations of the true values. 

FIGURE 10.17 Velocity contours in symmetry plane for a flanged rectangular opening with an aspect ratio of 2 1 by analytical and point sink methods. 

Flow Past a Point Sink A simple potential flow model for an unflanged or flanged exhaust hood in a uniform airflow can be obtained by combining the velocity fields of a point sink with a uniform flow. The resulting flow is an axially symmetric flow, where the resulting velocity components are obtained by adding the velocities of a point sink and a uniform flow. The stream function for this axisymmetric flow is, in spherical coordinates. 

FIGURE 10.19 Combination of a point sink flow field with a uniform flow field. 

Degrees of freedom of adsorbed ions, 928, 958 Delgani. 1290 Delocalization of electrons Destructive interference of waves, 789 Dendrites, electrodeposition. 1336. 1338 point sink during formation of, 1338 Deposrtion of metals, 1293 see also... 

For example, the treatment of diffusion that is to follow is solely restricted to semi-infinite linear diffusion, i.e., diffusion that occurs in the region between x = 0 and x —> +oo, to a plane of infinite area. Thus, diffusion to a point sink—called spherical diffusion—is not treated, though it has been shown to be relevant to the particular problem of the electrolytic growth of dendritic crystals from ionic melts. 

Analysis. To answer the question posed above, we treat the fuel cloud as a pseudo homogeneous or continuum phase (6, 7) with the individually burning particles treated as point sinks of oxidizer. Such an approach is rigorously defensible when the cloud is suflBciently dilute that ... 

The dependence of Hs/tin, on the velocity ratio is shown in Fig. 6.1 for particles of varying. size. To explain the shapes of these curves, we consider the case of fixed sampling velocity. For low mainstream velocities ( / ,/(/, - 0), the sample tends to be representative ( 7.v The sampling orifice acts as a point sink, and the streamlines of the flow are... 

Figure 7.4 Snapshots of the spatial distribution for the autocatalytic model (7.1) in the open blinking vortex-sink flow at time intervals equal to the flow period for a supercritical Damkohler number, Da = 7.0. Note, that after a transient time a time-periodic asymptotic state is reached where the autocatalytic growth, localized on the fractal unstable manifold, is balanced by the loss of product due to the outflow from the mixing region, in this case through the point sinks.

To have the similarity procedure valid, it is assumed that the wellbore radius is very small and a point sink is used to simulate the well. 

Oefiier PJ, Hunicke-Smith SP, Chiang L, Dietrich F, Mulligan J, Davis RW (1996) Efficient random subcloning of DNA sheared in a recirculating point-sink flow system. Nucleic Acids Res 24 3879-3886... 

In an introductory course on soil mechanics there is a limit to how far one can proceed. However, there are many more or less realistic problems which can be reduced to a single degree of spatial freedom onedimensional consolidation, flow of water towards a point sink or a line sink in a suitably infinite domain, stability of an infinite slope - these have already been mentioned. There are a number of examples of soil-structure interaction which can also be reduced to problems with a single degree of freedom. It is important to take whatever opportunities are provided by the skills and understanding that the students have developed to increase awareness of the interaction of soil and structural elements. It is not inevitable that the structural elements will always be significantly stitfer than the natural or man-made soils with which they interact (Muir Wood Nash 2000, Muir Wood 2004). 

To derive the boundary conditions on GH two flow conditions had to be superimposed and their boundary conditions combined. These two flows are the flow due to a point sink (which represents the fluid entering the channel) and the flow due to a moving plate in a corner (which represents the flow induced by the plate HOD at large distances from 0). The analytical expression for, Ip, on GH was derived separately for each flow and then the results were added together. 

The point sink flow was chosen to represent the fact that fluid was entering the channel through the gap OF and that, if a large enough scale were chosen, this would resemble a point sink at 0. Similarly the moving plate flow was chosen as, without the presence of the channel, this is the pattern of flow that the fluid would adopt. These two flow patterns are shown in Figure (4). By superposing these two flows the correct flow pattern was obtained. 

Figures 17.8 and 17.9 illustrate the concept of divergence. In a constant vector field (Figure 17.8), all the vectors point in the same direction and have the same magnitude. The divergence is zero, because there is no change in the vectors from one position in space to another. This might represent the w ater flow in the middle of a river. In contrast, as shown in Figure 17.9, an idealized point source of fluid (for example, a wellspring or fountainhead) or point sink (for example, a drainhole) causes the velocity vectors to diverge, to point in different directions from one point in space to the next. Near a point source...

The sink flow analysis, which assumes a purely extensional flow (i.e., no shear component), was presented by Metzner and Metzner (1970) to evaluate the extensional viscosity from orifice Apen measurements. For an axisymmetric contraction, the flow into the orifice is analogous to a point sink for a planar contraction flow, the analogy is with a line sink (Batchelor, 1967). In the case of axisymmetric contraction (Figure 7.8.1), the use of spherical coordinates and continuity gives the velocity components... 

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