Experimental research of bubble characteristics in narrow rectangular channel under heaving motion

► Experiment was carried out to reveal bubble characteristics under heaving motion. ► High-speed camera was mounted on heaving platform to capture the detail of bubbles. ► Bubble number density, bubble velocity and bubble diameter were investigated. ► Flow rate fluctuation and varied acceleration affected bubbles under heaving motion. ► A correlation was sought for fluctuation of bubble diameter due to heaving motion.