Development of Casbar: a Two-phase Flow Code for the Interior Ballistics Problem

Accurate modelling of gun interior ballistic processes aids in the design and analysis of guns and their propelling charges. Presently, the most accurate modelling of the interior ballistics problem is provided by two-phase, multidimensional computational fluid dynamics (CFD) codes. We present our development of a CFD code, Casbar, which solves a two-phase (gas/particulate) flow problem in axisymmetric geometries. Our model is based on the governing equations for two-phase flow derived from separated flow theory. A finite-volume discretisation of the governing equations is used. The resulting set of equations is solved with a timestep-splitting approach based on the separation of various physical processes. We also present the modelling for the component physics such as propellant combustion and interphase drag. In addition, the solver includes the motion of the projectile and its influence on the flow dynamics. The capabilities of the code are demonstrated with some verification exercises.

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