Aspects of Underwater Explosions and Preliminary Modeling in Impetus

The subject of this report, is the physics of underwater explosions (undex). The report has several goals: • 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 undex phenomena, which are useful for benchmarking purposes. In the second part (Chapter 5) we describe our attempts at modeling undex with the numerical code Impetus. Given that Impetus was not designed with undex phenomena in mind, the simulation capabilities are beyond what could reasonably be expected. Impetus is able to describe both the bubble dynamics and shock wave propagation qualitatively, although quantitatively there are still some discrepancies. However, it seems likely that these shortcomings can be overcome with updates to the Impetus code. A range of such improvements are suggested.