Immersed boundary methods for fluid-structure interaction problems in two-phase flows with phase changes*

Immersed boundary methods (IBM) have been extensively used to study a variety of flow problems, particularly cases involving complex boundaries undergoing large displacements and/or deformations. However, majority of applications are limited to single phase flows due to numerical challenges in modeling interaction of phase boundaries with the solid surface. Furthermore, existing techniques for multiphase IBM do not account for explicit contact line dynamics important in many physical problems. We will present a numerical framework which accounts for these mechanisms and is applicable to flows over irregular bodies. The mathematical model is implemented in a block-structured grid topology with adaptive mesh refinement (AMR) enabling selective refinement around the areas of interest. The contact line treatment is implemented by satisfying a dynamic contact angle boundary condition for the level-set function which is based on fluid properties and local flow velocity. We demonstrate the accuracy and robustness of the formulation in fluid-structure interaction problems involving phase changes through simulation of benchmark problems involving pool boiling over complex heater geometries.