Nonlinear fluid-structure interaction (FSI) is a dominating feature in many important engineering applications. Examples include underwater implosions, pipeline explosions, flapping wings for micro aerial vehicles, and shock wave lithotripsy. Due to nonlinearity and system complexity, most nonlinear FSI problems have not been thoroughly analyzed, which greatly hinders the advance of related engineering fields.

In this talk, a high-fidelity computational framework will be presented for challenging FSI problems involving strong shock waves, two-phase flows, large structural deformations, and fluid-induced fracture. Key components of this computational framework include: (1) an embedded boundary method for compressible flows based on the exact solution of local, one-dimensional, fluid-structure Riemann problems; (2) an extended finite element method (XFEM) for nonlinear structures, possibly with strong discontinuities such as cracking; (3) an accurate and robust algorithm for tracking the wet surface of a structure undergoing large deformations and topological changes; (4) a level-set technique for capturing fluid-fluid material interfaces; and (5) a robust and second-order accurate fluid-structure coupled time-integrator. The performance of this computational framework will be illustrated with applications to underwater implosions, pipeline explosions, and highly flexible aeronautical systems. This is a joint work with Professor Ted Belytschko's group at Northwestern University. The resulting software has been acquired by analysts and researchers at Naval Undersea Warfare Center, Naval Surface Warfare Center, Army Research Laboratory, and The University of Texas at Austin.