Aspects of Underwater Explosions and Preliminary Modeling in Impetus

The subject of this report, is the physics of underwater explosions (undex). The report has severalgoals:• Develop FFI’s basic knowledge of undex phenomena as part of the project ”1581, Våpenvirkningsmekanikk”.• Provide a general resource for any researcher interested in learning more about undex.• Perform preliminary undex simulations in Impetus to evaluate its current simulation capabilities.• Provide concrete benchmarks for the Impetus team in order to improve the code.The first part (Chapters 2–4) of the report is a detailed literature study of several important undexphenomena, which are useful for benchmarking purposes. In the second part (Chapter 5) wedescribe our attempts at modeling undex with the numerical code Impetus. Given that Impetus wasnot designed with undex phenomena in mind, the simulation capabilities are beyond what couldreasonably be expected. Impetus is able to describe both the bubble dynamics and shock wavepropagation qualitatively, although quantitatively there are still some discrepancies. However, itseems likely that these shortcomings can be overcome with updates to the Impetus code. A rangeof such improvements are suggested.