ON THE THEORY OF BULK CAVITATION
Abstract
When the compressive shock from an underwater explosion intercepts the free water surface, part of the shockwave energy is propagated into the overlying air and part is reflected back into the water. Early acoustic theories failed to describe the transmitted and reflected waves because acoustic theory implies a linear stress/strain relationship for the water--including the ability of water to withstand considerable tension. The analysis provided in the report assumes that the water can withstand no substantial amount of tension, so that an incident shockwave causes a surface layer of the water to rupture and spall upward. The region between the spall and the underlying (relatively) quiescent water has long been termed the cavitated region, and the entire process has been termed bulk cavitation. The energy contained in the incident compressive shockwave is temporarily stored in the kinetic and gravitational potential energy of the spall. When the spall falls back and impacts (water hammers) the underlying water this stored energy is reemitted. The spalled interface behavior is essentially different from the earlier acoustic interface picture, and the magnitude and shape of the pressure waves in the overlying air and those generated in the water at the time of spall impact are essentially different from that derived from the acoustic interface assumption.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1969
- Accession Number
- AD0704616
Entities
People
- Vincent J. Cushing