Interaction Fluide-Structure en Érosion de Cavitation
Abstract
This paper is devoted to cavitation erosion modeling. When liquid is subjected to pressure decrease, gas bubbles and vapor bubbles can appear. This phenomenon is called cavitation. In liquid high pressure zones, these bubbles may collapse and create a violent flow which can damage nearby solid wall. In industry, this phenomenon called cavitation erosion can reduce the lifetime of components of hydraulic machines. In biomedical, erosion by shockwave is used for ablation of human soft tissues or the destruction of kidney stones. In this numerical work, we focused on the collapse of one single air bubble near a deformable wall. This collapse is produced by the impact of an incident high pressure wave. Our work consists in developing a numerical fluid-structure coupling in order to compute the collapse of the bubble in the fluid code and the plastic deformation induced in the solid code. We chose a two-steps development strategy. The first step consisted in building a fluid code with a mobile mesh to integrate the displacement of the fluid-structure interface. This code was derived from the numerical model of Johnsen et al. at the University of Michigan. We implemented an ALE (Arbitrary Lagrangian Eulerian) method which allows us to describe the flow from an eulerian way on a fixed mesh to an eulerian way on a moving mesh. Then, the second step consists in the numerical modeling of elastic and plastic deformation of the solid during the bubble collapse. This latter was performed by the software CAST3M. Finally, a two-way coupling between the two physics was developed. The communication between the two codes is established thanks to MPI library. This coupling allows us to compute the collapse of an air bubble close to a deformable wall. We can study the deformation of this wall and relaxation effects on the pressure of the wave hitting the wall. This numerical tool is a first
step toward the understanding of the behaviour of compliant materials used to protect components from cavitation erosion and also toward the improvementof the benefits of biomedical shockwaves therapies.