This paper aims to investigate the aerodynamic variation patterns of twin-rotor vertical-axis wind turbines (TR-VAWTs) considering phase interference under different solidities, and to reveal the interactive mechanism between solidity, phase interference, and aerodynamic loads of TR-VAWTs. This paper first establishes a phase interference aerodynamic analysis model for TR-VAWTs based on two-dimensional computational fluid dynamics (CFD) methods. Secondly, experimental results are used to verify the accuracy of the numerical model. Finally, the variation patterns of aerodynamic forces and wake characteristics of TR-VAWTs under different parameters (solidity, initial phase angle) are explored. The results show that: (1) Each turbine of the side-by-side TR-VAWTs exhibits an increase in the energy utilization coefficient (C_P) in comparison with a single rotor. (2) The phase angle exhibits similar influence patterns on the efficiency of TR-VAWTs with different solidities. As the phase angle varies within the range of 30° to 60°, the efficiencies of rotor 1 and rotor 2 under medium-to-high tip speed ratios are both improved, while within the range of 60° to 90°, the efficiencies of each rotor generally decrease. (3) When TR-VAWTs with different solidities are at intermediate phase angles (90° for two blades, 60° for three blades, and 45° for four blades), the efficiencies of each rotor are basically consistent, which is conducive to power transmission. (4) If the intermediate phase angle is adopted as the reference configuration, the pressure influence on the turbines is minimized, which can not only make the power output more balanced but also improve the wake characteristics to a certain extent.

As core structural components for deep-sea oil and gas exploitation, deep-sea risers are continuously subjected to wind, wave, and current loads, which readily induce vortex-induced vibration (VIV) and further trigger structural fatigue damage. Furthermore, the progressive exploitation of deepwater and ultra-deepwater oil and gas resources has exacerbated the complexity and risk of riser VIV, rendering it a critical engineering problem that urgently requires effective solutions. This paper presents a comprehensive review of numerical studies on deep-sea riser VIV, systematically elaborating the fundamental principles, research advances, and application scenarios of three mainstream numerical approaches: semi-empirical models, computational fluid dynamics (CFD) models, and computational structural dynamics (CSD) models. The respective accuracy advantages and inherent limitations of each numerical method are thoroughly analyzed. Additionally, this review focuses on key research hotspots and challenging issues, including VIV responses of flexible risers, dynamic fluid–structure boundary coupling, internal–external flow coupling effects, wake interference of multi-riser systems, efficient VIV prediction, and vibration suppression optimization. The current technical bottlenecks in existing research are clarified. This study aims to provide a systematic theoretical framework and methodological reference for subsequent numerical investigations and engineering applications of riser VIV, and offer technical support for the optimal structural design and safety risk prevention of deep-sea riser systems.