ANALYTICAL RESEARCH ON THE WAVE DIFFRACTION OF ARC-SHAPED FLOATING BREAKWATERS

1. INTRODUCTIONBreakwaters are generally constructed for thedissipation and reflection of incident wave energyin order to decrease the wave height to protect thecoast against the erosion and to decrease the forceacting on the coastal structures . Compared…     

INTERACTION OF A CAVITATION BUBBLE AND AN AIR BUBBLE WITH A RIGID BOUNDARY

The motion of a spark-induced cavitation bubble and an air bubble near a rigid boundary is experimentally studied by using high-speed photography. Several dimensionless parameters are used to describe the geometrical configuration of the bubble-bubble-boundary interaction. The bubble-bubble interaction can be considered in two different conditions. The cavitation bubble will collapse towards the air bubble if the air bubble is relatively small, and away from the air bubble if the air bubble is relatively large. The two zones are identified in the bubble-boundary interaction, and they are the danger zone and the safety zone. The relative position, the bubble-boundary distance and the bubble-bubble distance play important roles in the bubble-bubble-boundary interaction, which can be considered in several conditions according to the responses of the bubbles. Air jets are found to penetrate into the cavitation bubbles. The cavitation bubble and the air bubble (air jet) move in their own way without mixing. The motion of a cavitation bubble may be influenced by an air bubble and/or a rigid boundary. The influence of the air bubble and the influence of the boundary may be combined, like some thing of a vector.     

THE COUNTER-JET FORMATION IN AN AIR BUBBLE INDUCED BY THE IMPACT OF SHOCK WAVES

The interaction of an air bubble (isolated in water or attached to a boundary) with shock waves induced by electric sparks is investigated by high-speed photography.The interaction is closely related to the counter-jet induced by the impact of shock waves.The formation of a counter-jet in an air bubble is related to the liquid jet formed in the same air bubble,but the mechanism is different with that of the counter-jet formation in a collapsing cavitation bubble.The formation of a counter-jet in an air bubb...