Visualization of shock wave propagation due to underwater explosion
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R E G UL A R P A P E R
Jayabal Rajasekar • Tae Ho Kim • Heuy Dong Kim
Visualization of shock wave propagation due to underwater explosion
Received: 28 April 2020 / Accepted: 29 May 2020 Ó The Visualization Society of Japan 2020
Abstract Researchers have a great interest in determining the characteristics of shock wave propagation by an underwater explosion. But it involves complex physical processes near boundaries during the underwater explosion. The major issues are explosions, fluid interactions, fluid–structure interactions, and shock wave propagation. In general, the underwater explosion leads to shock wave propagation and it moves toward two types of boundaries. The first one is the free surface of the water, and the second is fluid–structure interaction. The underwater explosion also deals with bulk cavitation behind shock waves. This paper deals with the shock wave propagation and bulk cavitation because of the underwater explosion near the free surface. The computation and analytical results of the underwater explosion were discussed and compared. Also, polynomial and Mie–Gruneisen (shock) equation of state (EOS) of water was implemented to determine the incompressible nature of water and to get realistic results. The results of both the EOS of water were compared against each other and validated against analytical results. These results show that the equation of state of water and water–air interface has a significant influence on the characteristics of the shock wave propagation and unsteady cavitation near the free surface. Keywords Underwater explosion Cavitation Water–air interface Shock wave propagation Equation of state
1 Introduction In underwater explosion related studies, researchers have been mainly interested in military-based applications initially, and later on, it was extended to other fields. The underwater explosion causes damage to both free surface and fluid–structure interaction area (Wang et al. 2014). But shock wave propagation characteristics vary with different medium and different equation of state for the same amount of explosive. The equation of state of water plays a crucial role in the calculation of damage caused by an underwater explosion (Steinberg 1987). Hence in this study, polynomial and Mie–Gruneisen equation of state for water was implemented and studied. The underwater explosion targets the object in water medium more than air. This is due to the higher acoustic impedance of water compared to air. Hence, more interest goes toward the characteristics of shock wave propagation during the underwater explosion. During the underwater explosion, a strong shock wave is initiated from the center. It propagates and reaches the free surface of the water. The free surface reflects the shock wave and forms rarefaction waves, which in turn leads to the formation of bulk cavitation near the water–air interface. The cavitation reloading has the same magnitude as initial shock loading, and it has a significant influence on the free surface (Brett
J. Rajasekar T. H. Kim
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