A new overset-grid-based hybrid method integrating PV-CFD (primitive variable-based computational fluid dynamics) and VTM (vorticity transport model) with high-order accuracy has been developed for high-fidelity simulation of rotorcraft flows. This approach solves the Navier–Stokes equations in the near-blade region and the vorticity transport equations in the far field, with vorticity treated as a primitive variable. The near-body solver captures vorticity generation, while the off-body solver efficiently handles vorticity convection. A new conservative form of the vortex transport equation is proposed, resulting in a hyperbolic system. A high-order flux reconstruction scheme is developed to solve the VTM equation on adaptive Cartesian grids based on this governing equation, effectively controlling numerical dissipation and preserving vortex structures with minimal diffusion. The overlapping PV-CFD and VTM grids enable bidirectional communication via the generalized Biot–Savart law and the pressure Poisson equation. The fast multipole method is employed to enhance computational efficiency. This hybrid framework allows precise tracking of vortex evolution—from formation at the blade tips, through convection, to interaction with subsequent blades—which is critical for predicting unsteady loads and noise. Several benchmark cases, including vortex propagation and leapfrogging vortex rings, are simulated to validate the method. The PV-CFD/VTM approach is further applied to simulate vortex flows around helicopter rotors in forward flight, where blade–vortex interaction (BVI) is a dominant noise mechanism. By accurately resolving vortex dynamics and pressure fluctuations, this study demonstrates that the proposed method provides an effective tool for capturing the rotor vortex flowfield, BVI phenomena, and associated noise generation.
Yang et al. (Sat,) studied this question.