Stream surface

Films of polyolefins, polyamides and poly(vinylidene dichloride) are made using this technique. As most of the films are used for flexible packaging, further down-stream surface treatments are usually applied to improve performance. For example, aqueous polymer emulsions, e.g., poly(vinylidene dichloride), or delaminated clay particles improve the barrier properties as will metallising with aluminium vapour. Corona discharge, causing slight surface oxidation, improves printability. 

From the definition of a particle used in this book, it follows that the motion of the surrounding continuous phase is inherently three-dimensional. An important class of particle flows possesses axial symmetry. For axisymmetric flows of incompressible fluids, we define a stream function, ij/, called Stokes s stream function. The value of Imj/ at any point is the volumetric flow rate of fluid crossing any continuous surface whose outer boundary is a circle centered on the axis of symmetry and passing through the point in question. Clearly ij/ = 0 on the axis of symmetry. Stream surfaces are surfaces of constant ij/ and are parallel to the velocity vector, u, at every point. The intersection of a stream surface with a plane containing the axis of symmetry may be referred to as a streamline. The velocity components, and Uq, are related to ij/ in spherical-polar coordinates by... 

No fluid crosses the sphere boundary. Hence the surface is a stream surface and since this boundary also cuts the axis of symmetry... 

The presence of high levels of suspended solids in stream surface water during storm episodes resulted in higher concentrations of adsorbed aluminum than in the absence of suspended solids (Goenaga and Williams 1988). The increased adsorption was not strictly linear, with higher concentrations of suspended solids due to variations in the particle size distribution and the nature of the particles. 

The qualitative analysis of backwater scenarios has been restricted to rectangular sections of great width. These equations are, however, applicable to any channel of uniform cross section, if y0 is the depth for uniform flow andyc is the depth that satisfies Eq. (10.118). The surface profiles can even be used qualitatively in the analysis of natural stream surfaces as well, provided that local variations in slope, shape, roughness of cross section, etc., are taken into account. The step-by-step integration method for the solution of nonuniform flow problems is not restricted to uniform channels and is therefore suited to backwater computations for any stream whatever. 

The pressure p and the stress components T>J, unknown at points M of the boundary surface Sq = Wq uXq (wall and free stuface), are determined from corresponding values of p and T on an internal stream surface S of the stream tube B using the following approximating equation... 

July 2006 Coastal waters influenced by Gulf Stream Surface 0.41-0.73 N2 MulhoUand et at. (submitted for publication)... 

Sulfur tolerances of Cu- and H-mordenite zeolite catalysts prepared by ion-exchange were examined in a fixed-bed flow-reactor system. Rates of reduction of NO over HM or CuHM with C2H4 and CuNZA with C3H6 are decreased by SO2 included in the feed gas stream. Surface areas and sulfur contents of the deactivated catalysts, their TGA and TPSR patterns and observations by XPS and Raman suggest the formation of a sulfur species on the catalyst surface in the form of sulfate (SO/ ) which causes the loss of NO removal activity of the catalysts. Data from Cu K-edge absorption spectra suggest sulfur electrostatically interacts with Cu ions on the catalyst surface. 

Napolitano GE, Richmond JE. 1995. Enrichment of biogenic lipids, hydrocarbons and PCBs in stream-surface foams. Environ Toxicol Chem 14(2) 197-201. 

Marmorino GO, and Trump CL (1994) A salinity front and rip near Cape Hatteras, North Caroline. J Geophys Res 99 7627-7637 Marmorino, GO, Jansen RW, Valenzuela GR, Trump CL, Lee JS, and Kaiser JAC (1994) Gulf Stream surface convergence imaged by synthetic aperture radar. J Geophys Res 99 18,315-18,328... 

Problems with Closed Streamlines (or Stream Surfaces)... 

It was already indicated in the preceding sections that this thermal boundary-layer structure does not occur when a particle (or body) is entirely surrounded by closed streamlines (or closed stream surfaces). In this case, the convection process near the body can no longer transfer heat directly to the streaming flow where it is carried into the wake, but instead circulates it only in a closed path around the body. Thus the heat transfer process is fundamentally altered, because heat can escape from the body only by diffusing slowly across the region of closed streamlines (or stream surfaces). Because the size of this region is independent of Pe, the steady-state temperature gradients will be 0(1), and we expect that... 

Assuming that this result is correct, it is very important because comparison with (9-230) or (9-274) shows that the rate of heat transfer from a particle (or heated body) to a surrounding fluid at high Peclet numbers depends critically on whether the streamlines (or stream surfaces) near the heated surface are open or closed. 

Before concluding the discussion of high-Peclet-number heat transfer in low-Reynolds-number flows across regions of closed streamlines (or stream surfaces), let us return briefly to the problem of heat transfer from a sphere in simple shear flow. This problem is qualitatively similar to the 2D problem that we have just analyzed, and the physical phenomena are essentially identical. However, the details are much more complicated. The problem has been solved by Acrivos,24 and the interested reader may wish to refer to his paper for a complete description of the analysis. Here, only the solution and a few comments are offered. The primary difficulty is that an integral condition, similar to (9-320), which can be derived for the net heat transfer across an arbitrary isothermal stream surface, does not lead to any useful quantitative results for the temperature distribution because, in contrast with the 2D case in which the isotherms correspond to streamlines, the location of these stream surfaces is a priori unknown. To resolve this problem, Acrivos shows that the more general steady-state condition,... 

Streamline implies the existence of a streamfunction, which we have seen to he true only for axisymmetric and 2D flows. In three dimensions, recirculating flows are associated with regions of closed stream surfaces, or pathlines. 

Well water samples were collected from residential taps prior to any in-place water softening units. Water samples taken during a spring flood water period were collected from inside taps after a full open flush of 30 minutes. This assured that the sample collected was groundwater withdrawn from the carbonate aquifer some distance from the well. Stream samples were taken at the center of the channel near the stream surface. The cross sectional stream samples were taken equidistant apart at 1/3 the water depth at each lateral position. Water samples were stored less than a week at 5°C. 

Spring Creek and its tributary, Slab Cabin Creek, are perched above the regional water table from Route 26 downstream towards Houserville. Water levels in well J of Figure 1 drilled within less than ten feet of Spring Creek commonly stand from 11 to 13 feet below the level of the stream surface as do water levels in test well K located along its valley slope or wall (Figures 1 and 5). Both wells were cased into bedrock and obtain water from solution openings. 

The mass flow rate to the sphere is found by calculating the rate at which mass impinges on the sphere between the stream surface IT = 0 and the stream surface defined by the loci of limiting trajectories, illustrated in Fig. 8.3.2 for the cylindrical case. The loci of limiting trajectories are determined by setting r = a + ap and 6 = ttII, whence... 

From the definition of the axisymmetric stream function and elementary continuity considerations, the volume flow rate between any two stream surfaces is simply IttA I. It follows that the mass flux of particles intercepted by the spherical collector is... 

By its physical meaning, the difference 2n y/- - y/2) is equal to the volume flow rate of liquid between two stream surfaces y/ = y/i and y/ = y/2. If the particles distribution far from the sphere is homogeneous, with mass concentration / q, the mass flux of the particles to the sphere is equal to... 

Freshwater and stream surface foam Three-step development in hexane/diethyl ether/acetic acid (98 2 0.3) acetone 100% chloroform/methanol/water (70 30 5) Napolitano and Richmond, 1995... 

The wear on the sidewalls of a chute will be less than that of the chute bottom. Roberts gives the following equation as a means of estimating the average wear on the sidewaUs assuming that the sidewall pressure increases linearly from zero at the stream surface to a maximum value at the bottom ... 

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