PIV measurement of pressure distributions about single bubbles

Measurements of velocity and pressure distributions around a bubble are of fundamental importance to model the forces acting on the bubbles and to verify detailed numerical methods for the prediction of flow in nuclear reactors. The measurements of velocity distributions around a bubble have been conducted to understand the interaction between liquid flow and bubbles. However there are few studies on pressure distributions around a bubble for the lack of measurement method. In this study, we developed a method for evaluating a pressure distribution by making use of velocity data obtained by a particle image velocimetry (PIV) or a particle tracking velocimetry (PTV), and applied it to laminar pipe flows, laminar flows around single particles and single bubbles in a pipe to examine its accuracy and applicability to the flow around single bubbles. As a result, we could confirm that the method can evaluate the pressure distribution in various laminar flows, provided that the velocity data possess a good quality and a flow of concern is two-dimensional. The proposed method therefore has a potential to provide the important information for modeling of the bubble motion and verification of CFD methods such as interface tracking and lattice Boltzmann methods.