An alternative mixed Eulerian Lagrangian approach to high speed collision between solid structures on parallel clusters

Abstract

The conventional approach to the analysis of collision problems, where a projectile penetrates a structure, involves a Lagrangian–Lagrangian contact driven methodology. Over the years there has been an enduring interest in collision type problems. However, since the events of 11th September 2001 (9/11) there has emerged a particular interest in projectile–structure collision events which simultaneously involve combustion, significant heat transfer and melting. These latter aspects are conventionally modelled using an Eulerian approach with computational fluid dynamics (CFD) software technology. Thus to model high speed collision in a comprehensive manner, it is necessary to take full advantage of the wide range of physics represented by CFD codes and explicit dynamic structural FE codes, which is not a trivial matter. The strain rates are so high in the neighbourhood of the collision that in representing the material behaviour as plastic one can formulate a model in an Eulerian manner. Thus, if the projectile–structure interaction can be captured adequately by an Eulerian approach, then one could use conventional CFD technology to model the whole spectrum of physics where combustion is simultaneously involved. As such, the prime objective of this paper is to implement and evaluate the use of conventional Eulerian CFD technology using well established free surface algorithms to capture the multi-material behaviour in a fixed grid environment and to evaluate the performance and whether the parallel scalability can be preserved. The paper is completed by a preliminary evaluation of whether compatible Eulerian and Lagrangian code modules can be coupled to capture the elastic behaviour of the structure far from the collision site.