Bubble deposition theory

The bubble deposition theory, which postulates bubble transverse migration due to transverse lift in combination with bubble lateral dispersion (Zun, 1985, 1988)... 

Flow of trains of surfactant-laden gas bubbles through capillaries is an important ingredient of foam transport in porous media. To understand the role of surfactants in bubble flow, we present a regular perturbation expansion in large adsorption rates within the low capillary-number, singular perturbation hydrodynamic theory of Bretherton. Upon addition of soluble surfactant to the continuous liquid phase, the pressure drop across the bubble increases with the elasticity number while the deposited thin film thickness decreases slightly with the elasticity number. Both pressure drop and thin film thickness retain their 2/3 power dependence on the capillary number found by Bretherton for surfactant-free bubbles. Comparison of the proposed theory to available and new experimental... 

With very large particles the liquid interlayer thinning process is complicated by the deformation of the bubble surface by an inertia impact of the particle. It was shown by Derjaguin et al. (1977) and Dukhin Rulyov (1977) that in the inertia-free deposition of small particles on a bubble surface its deformation under the influence of the hydrodynamic pressing force is insignificant. This third important feature facilitates the development of a quantitative kinetic theory of flotation of small particles. 

As it was pointed out in Chapter 8, the experimental verification of the theory of DAL of a bubble has so far been based on investigations of the effect of concentration and surface activity of a surfactant on velocity of buoyant bubbles of different size. As follows from the theory and from experiments, this effect is not very appreciable, it decreases sharply with the decrease of bubble size and of Reynolds number, and at Re < 40 it becomes unnoticeable at all. It was shown in preceding sections that the DAL structure determining the degree of retardation of surface motion has a strong effect on the deposition of small particles on a bubble surface. In this case it is important that papers by Reay Ratcliff (1973, 1975), Collins Jameson (1977), and Anfhms Kitchener (1976,1977) have demonstrated the possibility of... 

The flow of a long bubble in a capillary is a classical problem in fluid mechanics. Bubbles have been used as tracers in capillaries filled with liquid in order to determine liquid velocity. This application led to the discovery that when a wetting viscous liquid is displaced by a gas bubble in a capillary a liquid film is deposited on the wall. Initial experimental findings that the thickness of the film was proportional to Ca / were confirmed and extended to Ca= 10 [3]. In his pioneering approach, Brether-ton [1] assumed creeping flow in the liquid and used lubrication theory for the region of the film between the end of the spherical bubble cap and the flat film behind it to calculate the thickness of the film, the pressure drop and... 

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