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Theoretical Description of Motion of a Spherical Bubble in Neighbourhood of a Falling Particle
Basařová, P. ; Vejražka, Jiří ; Zedníková, Mária ; Hubička, M.
The aim of this work is to broaden the knowledge of the hydrodynamic interactions that occur between bubbles and solids of a comparable size. Focusing on collision processes between a single rising bubble with mobile surface and a larger falling solid spherical particle in stagnant liquid, the theoretical model describing the bubble trajectory is given here. The model is based on forces acting on the bubble and utilizes also equation for the bubble motion. The bubble is considered to be spherical and its motion is straight and rectilinear. The particle is spherical and moves vertically down with a steady velocity; the flow around the particle is axially symmetric.
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Experimental Study of Bubble Interactions with the Solid Surface
Zedníková, Mária ; Vobecká, Lucie ; Vejražka, Jiří ; Růžička, Marek
The experiments were carried out in a rectangular vessel equipped with a device generating the bubbles of defined size ranging from 0.4 to 2.0 mm (Vejrazka et al., 2008). Cleaned glass was used as a hydrophilic surface and polypropylene, polyethylene and Teflon were used as hydrophobic surfaces. Deionised water with addition of sodium dodecyl sulphate was used as liquid. The collision and attachment process was observed by means of high speed camera. The following quantities were evaluated from the image sequences: impact and rebound velocities of a bubble, maximal bubble deformation during the contact with the surface and the time required for three-phase contact line formation. The experimental results were compared with our previous investigations (Fujasova-Zednikova et al., 2009).
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Research of Multiphase Systems at ICPF AS CR Prague
Zedníková, Mária ; Růžička, Marek ; Drahoš, Jiří
The aim of this contribution is to present to the Czech waste water treatment community the multiphase flow research at the ICPF ASCR. The goal of the research is to understand the basic physical mechanisms of flow systems with two or more phases. The interest covers a broad range of the multiphase flow systems; for instance: production and hydrodynamics of bubbly mixtures, flow regimes and their identification, effect of control parameters on the flow regimes, mass transfer in gas-liquid systems, bubble formation, coalescence and break-up, hydrodynamic interactions of bubbles, interaction of bubbles with solid particles, sedimentation of polydisperse mixtures etc.
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The Study of Interactions of Bubbles with Solid Surface. The Effect of Surfactant Concentration and Type of Solid Surface
Vobecká, Lucie ; Zedníková, Mária ; Vejražka, Jiří ; Růžička, Marek
This contribution deals with experimental study of interactions between a bubble and a solid horizontal surface. The influence of surfactant concentration in liquid and of material of the solid surface on the interaction is observed. It is observed that the material of solid surface has not significant influence on the hydrodynamics of impact of bubble on a wall. The impact velocity is not affected by surfactant presence because the liquid flow around the bubble moves adsorbed surfactants to rear of the bubble and the interface at top of the bubble stays mobile. The presence of surfactant has strong effect on the bubble rebound, as the rebound velocity and the maximal distance of bubble from the wall decreases with increasing surfactant concentration. No bubble rebound is observed at high concentration of surfactant.
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