Mechanical and Civil Engineering Seminar
*Connection details for this online presentation will be posted when available
Cavitation describes the formation, growth, and collapse of bubbles in a liquid when exposed to rapid pressure or temperature variations. The final step of the bubble collapse consists of a rapid compression of the internal gas, which results in high amplitude pulses of mechanical and thermal energy — such as shocks of up to 200 MPa, liquid jets ("microjets") of up to 300 m/s, and local temperatures of thousands of Kelvin. This talk will start with an overview of several engineering and biomedical applications that require carefully controlled cavitation for high-precision material modifications, including ultrasound cleaning, underwater laser cutting, shock wave and laser lithotripsy, and histotripsy. The talk will focus on discussing recent efforts on modeling and simulating the multiphysics problem that dominates these applications, including the coupling of multiple materials, phases and physical fields (e.g., mechanical, mechanical, electromagnetic), phase transitions (e.g., vaporization), and material damage and failure under shock loads. The FIVER ("FInite Volume method based on Exact two-phase Riemann solvers") computational framework recently developed by the speaker and co-workers will be introduced, including the use of staggered time-integrators to couple an Eulerian compressible fluid solver with a Lagrangian solid mechanics solver, the use of embedded boundary and level set methods to track material and phase interfaces, and the construction and solution of one-dimensional two-phase Riemann problems to transfer shock loads. Several numerical experiments in the context of lithotripsy and underwater explosion/implosion will be presented to assess these models and numerical methods, and to demonstrate the two-way coupling between cavitation bubble dynamics and the dynamic response and failure of various solid and soft materials.