Split flow pattern

Fig. 13. Bubble column flow characteristics (a) data processing system for split-film probe used to determine flow characteristics, where ADC = automated data center (b) schematic representation of primary flow patterns.

Horizontal split-case The flow pattern through a horizontal split-case pump is radically different than that through an end-suction pump. Inlet and discharge flow are in the same plane and almost directly opposite one another. This configuration, illustrated in Figure 44.22,... 

Figure 4.23 Near-ideal multi-lamination flow patterns in the second-generation caterpillar mini mixer as a result of introducing a splitting plate and improving micro structure geometry [50],...

Simulation of cross-sectional flow patterns without splitting plane and for non-separated SAR flows... 

It is used to eliminate or reduce weld lines. Two separate injectors or one injector with a splitting device are used to move melt in and out of the cavity from opposite sizes. This type action repeats and is programmed to maximize the best melt flow patterns. 

The flow pattern may change with length. Satterfield and Ozel [7] observed that as bubbles and slugs flow down, a liquid ring frequently appears within a bubble. The ring grows in thickness and finally fills the complete cross section of a capillary, thus splitting the bubble in two. 

The stirrer is thereby approximated for the calculation of turbulent flow by a tangential jet [288, 441], and for laminar flow by a cylinder [46-48, 50, 98J. The stirred tank is split up into a number of zones, to which one can assign characteristic flow patterns and analytically describable velocity profiles. Models with up to 8 zones have been developed, but only two models (for stream ejected by the stirrer and for circulation flow) have been able to explain the experimental results satisfactorily [440]. 

The flow pattern is also modified when reactors other than straight open tubes are used. In coiled reactors, all fluid elements cannot be displaced on parallel trajectories, as the distances travelled are dependent on their relative positions. This results in split circulation of the fluid elements (Fig. 3.5), which is a consequence of the establishment of secondary flows [48]. The effect becomes more pronounced at higher flow rates. Its beneficial influence on mixing conditions, hence, on sample broadening and sampling rate, has often been emphasised [10,49]. An analogous but more pronounced effect is observed with knitted (or 3-D) reactors [50]. 

In the present extrusion of HDPE ribbons, the deformation patterns were examined by the deformation of parallel ink marks preimprinted on the surface of a HDPE (Figure 1-d). At EDR >12, the low and high MW HDPE exhibited a typical shear parabola and a W-shape deformation profile, respectively, with both characteristics enhanced at higher EDR as shown in Figure 2. These characteristics of the deformation patterns are in well agreement with our previous observations (3) and further confirm the previous conclusion that there is no significant effect of cutting a billet into two halves and/or coextrusion of a film with the split billet halves on the deformation flow patterns. 

A remarkable analysis of the role of hydrodynamics in LB depositions was done by de Gennes (1986). This analysis concerns only deposition during removal of the solid substrate, de Gennes recognizes that the only flow pattern that would allow Y-deposition is a split-ejection streamline in the liquid phase. However, he uses as a reference the work of Huh and Scriven (1971), but their hydrodynamic theory predicts a rolling motion in the liquid phase. 

Petrov and Petrov (1998) developed a molecular hydrodynamic theory of film deposition during removal. Their theory correctly assumes a flow pattern - which we identified as a split streamline - between the solid substrate and the monolayer in Figure 10.5 (c). This pattern is indeed the necessary pattern for successful deposition during removal, but it is not the only flow pattern for solid removal at all dynamic contact angles. Petrov and Petrov (1998) address the kinetics of water removal between the solid and the monolayer and the formation of wet or dry monolayers depending on the amount of water entrained. 

Figure 10.4 Schematic representation of flow patterns near a moving contact line during immersion of a solid substrate into a pool of liquid, (a) Split-injection streamline in phase B and rolling pattern in phase A. (b) Transition flow pattern with motionless interface and rolling motion in phases A and B. (c) Rolling motion in phase B and split-ejection streamline in phase A...

When a wetting solid is removed from the liquid phase, the flow pattern in the liquid phase is the split-ejection streamline pattern shown in Figure 10.5 (c). The interface liquid-air moves toward the contact line and a Z-type LB deposition is possible. During removal, transfer ratios of the monolayer show a strong dependence with the relative... 

Region IV is the window of operation for successful deposition of Y-type films. The flow pattern in this region is typical during removal of solids with dynamic contact angles 0 < < 90°. The split-ejection streamline is in the liquid phase and the interface... 

For very small dynamic contact angles, the liquid is not completely removed by the split streamline and it is entrained between the film and the solid surface, creating what is known as a wet LB film. Water trapped between the solid surface and the LB monolayer prevents adhesion and is a leading cause of monolayer instability. Petrov etal. (1980) sketched the flow pattern near the moving contact line. The flow pattern is the one described here for region IV. The authors, however, reference Huh and Scriven (1971)... 

While the net flows patterns for each structure are now clearer, it still remains difficult to comprehend the effects of changing the reflux in one CS in the rest of the column. The reflux ratio in a specific CS is an important parameter in finding feasible structures and therefore it is necessary to fully understand these effects. As shown in previous chapters, the reflux in a specific CS is a limitless parameter valid anywhere from negative to positive infinity. Notice howev that in the side-stripper configuration, for example, that the liquid stream is split into two parts. 

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