MEchanics GAthering -MEGA- Seminar: Simulating fluid-structure interactions with many highly deformable solids

Abstract Fluid-structure interactions (FSI) are abundantly observed at all scales, ranging from microbial locomotion to geological formations. The governing equations are only analytically trackable in the simplest cases, making simulations key to understanding this important class of problems. Conventional computational methods often create a dilemma for FSI problems. Typically, solids are simulated using Lagrangian meshes that move with the material, whereas the fluid is simulated using an Eulerian mesh, i.e. a fixed spatial grid. Thus, FSI methods often require some type of interfacial coupling between the fluid and the solid phases. Generating solid meshes and maintaining their quality often prove challenging, especially in mid to high Reynolds number flows, or when objects have complex geometries. Detecting contact between objects can also become a bottleneck when simulating many-body problems. We develop a fully Eulerian FSI method called the reference map technique (RMT) that addresses these challenges. The method makes use of the reference map fields on a fixed fluid mesh that allow easy switching between the physical space and the reference space in the solids. We use examples such as an elastic sphere in a 3D lid-driven flow and settling of many particles to demonstrate that the RMT is particularly well suited for simulating FSI with soft, highly deformable solids, as well as many-body contact problems.