A sharp MLS penalty immersed finite element method for fluid-structure interaction of highly deformable slender body in turbulent flow

This paper presents a new computational approach to simulate challenging fluid-structure interactions (FSI) between fluids and slender deformable structures. Key innovations address limitations of standard immersed boundary methods, including spurious forces, stability at low density ratios, and accuracy at high Reynolds numbers. The method couples a sharp interface immersed boundary technique with detached eddy simulation turbulence modelling to enable precise FSI for high Reynolds number flows. A strong coupling partitioned algorithm stabilized by Aitken relaxation significantly enhances stability for low density ratios down to 1. A moving least square compact support domain approximation reduces spurious oscillations from moving geometries while providing second-order accuracy. Adaptive mesh refinement imposes jump conditions on slim deformable bodies and minimizes grid leakage. The proposed method is evaluated on three conventional FSI benchmarks and four experimental cases, confirming its robustness, accuracy, and stability in low and significantly high Reynolds numbers. A more complex fluids engineering case is considered last to test the solution under challenging conditions with fast moving solid boundaries and fast flowing fluid. A thin deformable membrane is forced through a submersible centrifugal pump under standard operating conditions. The solution is shown to produce a stable solution with good collision handling ability.