Interpolation-Free Immersed Boundary Method Implementation Using the Space-Time Conservation Framework in UNICONES

An Immersed Boundary Method (IBM) has been implemented in the in-house solver UNIfied CONservation Equation Solver (UNICONES), which is based on the space-time Conservation Element and Solution Element (CESE) method and offers high numerical fidelity by treating space and time as a unified computational domain. The IBM approach in this framework uses a volume of fluid (VoF) equation to identify the region of different phases (such as solid-fluid and/or liquids-gases) and their interfaces, eliminating the need for body-fitted meshes or interpolation near phase interfaces. Feedback forcing strategy is employed to impose solid motion and interfacial effects between phases, enabling simulations involving both stationary and moving bodies as well as multiphase flows. Validation and demonstration cases include flow past a stationary cylinder, flow past a rotating cylinder and subsonic flow over a multi-element airfoil (30P30N). These simulations capture critical flow structures such as vortex shedding, asymmetric wakes and pressure coefficient distribution. Additionally, multiphase flow capabilities are demonstrated through simulation of a falling drop merged into liquid film. The results attest the robustness and versatility of the implemented IBM framework in handling complex fluid-solid and multiphase interactions using arbitrary structured or unstructured background meshes including the commonly-used Cartesian ones.