Vortex induced Vibration response of steel catenary riser under linear shear flow

Here, a spatial distribution-based wake oscillator model was used to numerically simulate 3 D vortex induced Vibration (VIV) response characteristics of a slender flexible catenary riser. The numerical model considered effects of riser local inclination angle and relative velocity of fluid-structure field on hydrodynamic load. Coupling wake oscillator and riser motion governing equation, a time-domain dynamic model of catenary riser was constructed under non-planar inflow. The 2nd-order precision finite difference method and the 4th-order Runge-Kutta method were used to solve the coupled Vibration equation. By comparing Simulation results with test ones, the reliability of the model was verified to a certain extent. Subsequently, for real scale risers, effects of flows with different shear degrees on VIV amplitude, response propagation waveform, structural Vibration frequency, locking interval and energy transfer coefficient of fluid-structure field were compared. Numerical results showed that compared to uniform flow, riser under linear shear flow exhibits more complex Vibration response characteristics; with increase in shear degree of inflow, Vibration amplitude gradually decreases, and locking zone exhibits regional characteristics along riser axis direction accompanied by significant multi-frequency Vibration responses. © 2025 Chinese Vibration Engineering Society. All rights reserved.