Influence of Shock-Induced Air Bubble Collapse Resulting from Underwater Explosive Events.

摘要

During an underwater explosion (UNDEX) event, a cavitation zone is created which alters the shockwave propagation parameters through this region. A cavitation zone is generally comprised of air bubbles whose material properties closely resemble water vapor. Multiple scenarios were created using these properties to simulate the presence of bubble regions during an UNDEX event. Initial simulations involved large rectangular bubble regions which reduced the pressure from the initial shockwave, providing a buffering effect. To better simulate homogeneous air bubbles, additional studies were conducted using circular shapes of varying diameters. For small diameters, the pressure greatly increased in the immediate vicinity of the bubble. These bubbles were studied further using a refined Eulerian mesh. For large diameters, a second pressure peak was encountered, but the pressure magnitude remained roughly the same. Since large homogeneous bubbles are not typically prevalent in nature, a small region of several smaller bubbles was evaluated. This data showed that multiple small bubbles result in an overall lower pressure when compared to a single air bubble of similar area. The pressure increase incurred from the initial shockwave interaction with these air bubbles may be minimized by increasing the distance from the bubble center.