Critical bubble diameter for the reversal of lift force acting on single air-water bubble

Viscosity, shear ratio, bubble injection method, and surface contamination were considered as possible reasons on the discrepancy. Therefore, on the universal understanding of lift force acting on bubble, now it is very unclear state. To solve the problem, experimental basis are crucial due to computational limitations of current CFD method. In this paper, experimental results on bubble shift in shear flow similar to Li et al. are presented. Although similar test condition is tried, this kind of experiment is valuable to do, due to rareness of the experimental data. Shift of air-water bubble in linear shear flow is experimentally investigated. It is observed that similar trend to results of Li et al.(2016) can be well reconstructed from the current experimental setup. Based on the experimental results, it seems that critical bubble diameter for air-water bubble is lower than 2mm like as transitional diameter for wake instability of free rising air-water bubble.