Bubble tracks

Whitehead (1978) found patterns of bubble tracks in a large 1.2 m square bed similar to Werther preferred bubble tracks near the walls and comers of a shallow open bed and merging of bubbles toward the bed center at higher elevations. Nguyen, Potter, and Whitehead (1979) also found that a horizontal tube bank in the large bed caused smaller bubbles which appeared in more random locations across the upper surface of the bed. This work was carried out for fine solids at low superficial velocity, 15 cm/sec, and modest bed depths. 

The second example concerns bubble coalescence. Experience has shown that in fresh water, air bubbles are much less stable than in sea water. Those Involved in boating may have observed that sp>eedboats in sea water create much longer bubble tracks. What is the origin of this difference ... 

Gating and venting must be done with an eye to the effects of reinforcement orientation and bubble track formation downstream of flow obstructions. The size and number of vents required depends upon the volume of the part and the rate of fill used in addition to the shape of the part itself. Preferred vent geometry is a groove. 003-.005 inches deep and 3/8 inches wide. This does not permit excessive flash and polymerizes closed rather quickly. 

Thomas GB Jr, Finney RL (1996) Calculus and Analytic Geometry. Addison-Wesley Publishing Company, 9th Edition, Reading, Massachusetts Tomiyama A, Miyoshi K, Tamai H, Zun 1, Sakaguchi T (1998) A bubble tracking method for the prediction of spatial evolution of bubble flow in a vertical pipe. Third International Conference on Multiphase Flow, Lyon, France Trapp JA (1986) The mean flow character of two-phase flow equations. Int J Multiphase Flow 12(2) 263-276... 

The foregoing observations can be interpreted in terms of the bubble behavior in fluidized beds. Werther and Molerus (1973) reported that very close to the distributor region, intensified bubble activity exists in an annular region near the wall. As bubbles detach and rise, they tend to move toward the center. If the bed is sufficiently deep, they will eventually merge at the center. Because the solids are carried upward in the wake of the bubbles, they basically move along the bubble tracks. Therefore, the solids would... 

Darton et al. (1977) assumed that the bubbles are lined up as elose together as possible, as shown in Fig. 13. They also defined a so-ealled catchment area for each particular bubble track. The bubble frequency can then be calculated by Ub/2R with the bubble velocity =0Jll(gD y. The bubble flow in each track can be calculated as follows assuming the two-phase theory. 

A stochastic bubble-tracking method incorporates the instantaneous gas flow velocity, for example, m = m -L in the x direction. The magnitudes of u, and w during the lifetime of a fluid eddy through which a bubble traverses are sampled assuming that they obey a Gaussian probability distribution. In the x direction. 

Tomiyama A, Miyoshi K, Tamm H, Zun I, Sakaguchi T (1998) A bubble tracking method for the prediction of spatial evolution of bubble flow in a vertictil pipe. In Third international conference on multiphase flow, Lyon, France... 

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