Transverse flow

It has recently been demonstrated that similar effects may be generated by a superhydrophobic Cassie surface. The transverse flow due to surface anisotropy is generated only in the vicinity of the wall and disappears far from it, which has already been observed in experiments. In other words, the effective velocity profile is twisted close to the superhydrophobic wall (see Fig. 2.15a). 

To evaluate the transverse flow the velocity profile has been integrated across the channel to obtain the flow vector  

To optimize the texture, channel thickness, and the angle 9 between the directions of stripes and the pressure gradient, Qy/Qx is maximum, providing the best transverse flow. 

The maximization in respect to 9 indicates that the optimal angle 

We conclude, therefore, that since H is fixed, the maximal Qy/Qx corresponds to the largest physically possible b, that is, the perfect slip at the gas sectors. 

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A. V. Lemmo and J. W. Jorgenson, Transverse flow gating interface for the coupling of mictocolumn LC with CZE in a comprehensive two-dimensional system . Anal. Chem. 65 1576-1581 (1993). 

In open rod bundles, transverse flow between subchannels is detectable by variations in hydraulic conditions, such as the difference in equivalent diameter in rod and shroud areas (Green et al., 1962 Chelemer et al., 1972 Rouhani, 1973). The quality of the crossflow may be somewhat higher than that of the main stream (Madden, 1968). However, in view of the small size of the crossflow under most circumstances, such variation generally will not lead to major error in enthalpy calculations. The homogeneous flow approximation almost universally used in subchannel calculations appears to be reasonable (Weisman, 1973). The flow redistribution has a negligible effect on the axial pressure drop. 

Zamodits, H. and Pearson, J. R.A., Flow of Polymer Melts in Extruders. Part 1. The Effect of Transverse Flow and of Superposed Steady Temperature Profile, Trans. Soc. Rheol., 13, 357 (1969)... 

Along the screw of an extruder both transport flow and transverse flow occur. The latter provides a circulation flow, which promotes mixing and homogeneity. 

The Matsuzaka Elbow-Jet classifier (Fig. 11) is based on a transverse flow principle (26). The stream of feed particles are accelerated to minimize the effect of gravity, and introduced into an air jet at right angles. The particles are fanned out in the classification zone with the trajectories for particles of the same hydrodynamic behavior, ie, size and shape, being the same. Classification is achieved by mounting one or more cutters in the classification zone, thus dividing the feed into two or more fractions. A stream of fine particles of less than 5 Jm can be produced in this manner. 

A coordinate of a point, containing liquid moving with velocity vav is designated Zav- As the front line is assumed to be straight, the fountain effect is described by the assumption that transverse flow occurs along this line from the part of the cross-section where the velocity is high... 

D.V. Khakhar, J.J. Me Carthy, T. Shinbrot, J. Ottino, Transverse flow and mixing of granular materials in a rotating cylinder, Phys. Fluids 9 (1997) 31—43. 

By using the rectangular transverse-flow module developed by TNO (The Netherlands), an industrial membrane gas absorption unit for ammonia recovery has been installed in The Netherlands [21]. Also, a unit for C02 removal has been tested [22]. 

Koopman, C. and Witkamp, G.J. (2002) Extraction of heavy metals from industrial phosphoric add in a transverse flow hollow-fiher membrane contactor. Separation Science and Technology, 37,1273. 

In an electrohydrodynamic mixer, a DC electric field (400 kV/cm) is applied on two electrodes across a channel to induce secondary transverse flow for solution mixing. Explain why there is no problem of electrolysis. (2 marks)... 

Figure 9.6 Principle of operation of a kneading block distributive mixing results from transverse flow...

In the fourth subtechnique, flow FFF (F/FFF), an external field, as such, is not used. Its place is taken by a slow transverse flow of the carrier liquid. In the usual case carrier permeates into the channel through the top wall (a layer of porous frit), moves slowly across the thin channel space, and seeps out of a membrane-frit bilayer constituting the bottom (accumulation) wall. This slow transverse flow is superimposed on the much faster down-channel flow. We emphasized in Section 7.4 that flow provides a transport mechanism much like that of an external field hence the substitution of transverse flow for a transverse (perpendicular) field is feasible. However this transverse flow—crossflow as we call it—is not by itself selective (see Section 7.4) different particle types are all transported toward the accumulation wall at the same rate. Nonetheless the thickness of the steady-state layer of particles formed at the accumulation wall is variable, determined by a combination of the crossflow transport which forms the layer and by diffusion which breaks it down. Since diffusion coefficients vary from species to species, exponential distributions of different thicknesses are formed, leading to normal FFF separation. 

In catalyst packings transverse flow components arc automatically established as a result of the nonuniform arrangement and the twisted flow around the pellets. Hollow and full cylinders with a length-to-diameter ratio of 1 3 are particularly effective in this respect. Despite the fact that radial heat transport takes place... 

In transverse flow, the buoyant motion is perpendicular to the forced motion. Transverse flow enhances fluid mixing and thus enhances heat transfer. An example is horizontal forced flow over a hot or cold cylinder or sphere. 

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