NICOP - The physics of shock wave propagation through air and water medium
Abstract
Shock waves are typically generated as a result of explosions which propagate through a medium (air, wateror soil) before striking" a structure and causing catastrophic failures. When the shock wave encounters anobject or an interface in its propagation path some part of it is reflected whereas some part of it istransmitted. This transmitted energy to the structure results in damage which in some cases is desirablewhereas in some other cases is undesirable. Generally energy from a shock wave is attenuated in themedium prior to it hitting the structure. Usually researchers are concerned with effect of shock wave on astructure/material or atmost on medium-structure interaction but very few researches have concentrated onpropagation of shock wave through a medium. Propagation of shock wave has its own challenges andcontrary to the common belief it may not always lead to attenuation of shock wave intensity." For exampleif a strong shock wave is transmitted in liquid water, the liquid water medium may itself undergo phasetransformation"" to that of ice VII (the densest form of ice) [1,2] and since the density of this ice phase ismuch higher than that of water the sh""ock wave speed should increase rather than decrease. Another examplemaybe when a strong shock wave propagates through air, the air"" molecules may ionize [3,4] leading tochemical reactions between them. The effect of chemical reactions on impulse transmission to" the structureis not known as of today. Another area that is not exhaustively researched is what happens at the interfaceof two mediums as the shock wave passes in between the two. These situations do arise in reality such asinteraction of a cavitation bubble with the surrounding water medium and also in transmission of explosioninduced shock wave in air to that of the water medium. Moreover it is also not known if the existingcontinuum theories of cavitation bubble propagation along with its release of secondary shock waves aresufficient for all temperature extremes as faced by the navy (such as -30 to 60 deg C). These areas of shockwave propagation through a medium are typically un-ventured research domains and thereby the proposedfundamental research which aims to answer the above posed questions is challenging and innovative.Molecular dynamics and density functional theory based simulations of shock waves through differentmedia under different environmental conditions would be carried out as part of this research to answer theabove questions.The topic of shock wave propagation through a medium not only has direct and applied relevance to thenavy (in terms of impulse transmission to the structure which can not only be used for the purpose of blastmitigation but also for inducing in casualties to the enemy) but also has a fundamental component to it (inwhich interesting physics are yet to be discovered). This outcome of this research proposal could either beused to develop better mitigation technologies (for defence) or better disaster amplification technologies(for offence) as the situation demands. This project can be aligned with ONR programs Code 33 for theunderw"ater shock propagation part, Code 35 for shock propagation through air and Code 30 for mitigationtechnologies.ONR Program Officer" associated with the proposal is Dr. Ramesh Kolar.The desired outcome of this fundamental research effort would be conference prese"ntations, journalpublications as well as preparation of reports which could provide a baseline for development of mitigationtechno"logies against shock wave loads and/or development of methodologies by which maximum casualtycan be induced upon the enemy.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 20, 2018
- Source ID
- N629091812057
Entities
People
- Nilanjan Mitra
Organizations
- Indian Institute of Technology Kharagpur
- Office of Naval Research
- United States Navy