Entrained Air in Linearly Accelerated Water Flow

The reviewed theoretical literature has suggested that a gas bubble introduced to a linearly accelerated liquid flow will soon lead the flow, and ultimately approach an equilibrium state (comparable to the terminal velocity stage) when the ratio of the relative velocity to the liquid velocity takes a constant value. To inspect the validity of these findings, the present experimental tests were performed by injecting single air bubbles of diameters varying between 0.057 in. to 0.250 in. (1.45 mm to 6.35 mm) in a water flow at constant velocity gradient. By photographic means, the motion of these bubbles was recorded. The analysis of these films has shown that, without exception, all bubbles in this work have led the velocity of the water flow and hence confirmed the theoretical findings.