A Multi-Point Coupling Strategy for the Analysis of Spatially Distributed Rotor–Clearance Flow Interaction

Abstract This work presents a novel multipoint coupling scheme between the rotor and clearance flow, particularly for scenarios where the flow extends over a significant portion of the rotor length. The rotor system is modeled using one-dimensional beam elements, while the clearance flow is represented by two-dimensional bulk-flow equations discretized with finite elements. The proposed method employs the shape functions of the beam elements to achieve consistent coupling. The entire displacement field is mapped onto the fluid domain, and the resulting fluid forces and dynamic coefficients are distributed to the rotor nodes in a multipoint manner. Numerical results for pressure and velocity show significant differences compared with the conventional single-point coupling approach, which imposes a uniform displacement across the entire fluid domain. The proposed framework yields converged solutions as the number of beam elements increases and ensures consistency even with a nonmatching interface between the rotor and fluid domains. Finally, static and dynamic analyses of a rotor–hydrodynamic bearing system with the bulk-flow model are presented. The load-carrying capacity and natural frequencies vary with the clearance–radius ratio in the bulk-flow model, highlighting the importance of multipoint coupling.