An efficient sharp-interface immersed boundary method for complex moving boundary flows based on adaptive Cartesian grids

Accurate moving-boundary treatment is a core challenge in flow simulations for maneuvering micro aircraft and high-speed trains. Adaptive Cartesian grids suit large-amplitude, high-frequency motions via automated meshing and dynamic refinement, but their boundary treatments suffer from limited accuracy, low robustness, or high computational cost now. To address this issue, this paper proposes a novel ghost cell interpolation approach based on the intersection point method to conduct extensive simulations of low-Mach laminar flow large-amplitude motion problems. The proposed method was first validated through accuracy tests of the classic flow past a cylinder. The results show that the immersed boundary method can achieve a precision between two and third order in the flow field, verifying its certain efficient high-order interpolation characteristics. Furthermore, through simulations of a series of typical cases, the high accuracy of our method in unsteady flow simulations is further confirmed. In addition, the developed high-order interpolation method for new sub-cells reduces the total number of cells in dynamic adaptive grids by more than 2/3, significantly improving computational efficiency. The method developed in this study has promising application potential in the design of advanced equipment, such as aircraft with sudden attitude changes, and rapidly rotating machinery, as well as in high-fidelity and automated flow field simulations.