The paper is focused on studies of particle's path deflection near the wall. Particle is modeled by a rigid sphere suspended on the thread. A specially designed rig has been constructed where systematic experiments were done to obtain sphere trajectories for its three different sizes. Mathematical analysis led to correlation describing the influence of wall on particle movement in function of initial distance of the sphere to the wall and its Reynolds number. The analysis was based on original model postulated by authors. Comparisons of experimental data against correlations available from literature shows a satisfactory agreement.
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The aim of present work is investigation focused on experimental verification of forces acting on bubble flowing along the wall and subsequent implementation of the findings into the model of void fraction distribution, developed earlier by one of the co-authors [6]. In experimental investigations the bubble is represented by a solid sphere suspended on a thin string. Authors are convinced that the presented model of a bubble motion captures at least a qualitative behaviour of a bubble in the bubbly flow and will compliment the transverse force balance acting on the bubble. Such transverse balance of forces forms one of equations involved in the model of void fraction developed by Mikielewicz [6]. Presented results of experimental research show periodic character of sphere movement (simplified bubble model) along the wall of vertical channel, which is in line with findings of the experiments preformed on bubbles in vicinity of wall. Sphere trajectory visibly changes, which are caused by non-uniform velocity distribution of fluid around the sphere related to non-uniform pressure field around it, giving in such a way rise to the repelling force. The wall force was introduced to the model of void fraction distribution and improved results were obtained.
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