Effect of temperature variation on the fluctuation of a sessile bubble rising in a stagnant medium

Abstract

Abstract The present work represents an experimental investigation of the flow dynamics and features of a rising isolated bubble within a stagnant water column under variable temperature. The experimental tests have been carried out using high speed imaging with backlighting. Five different values of the water temperature (namely 10, 20, 30, 40, and 50°C) have been implemented during the experiments. The studied features are the bubble size (diameter and circumference), bubble shape (sphericity and aspect ratio), bubble rising velocity, in addition to the bubble zigzag motion features (angle, maximum horizontal diameter, velocity, and occurrence time portion). The obtained results showed that as the temperature increases, the degree of bubble zigzag motion from its vertical path increases, which means the flow of the bubble becomes less stable. Bubble diameter is shown to be irresponsive to temperature for small value increase, whereas, for greater temperature magnitudes (from 30 to 50°C) it is shown to be proportional. All other features are shown to be proportional to temperature variation. The zigzag motion features are also shown to be proportional to water temperature variation except the average occurrence time is inversely proportional to this change.