A pressure-based actuator line approach for diffuser modeling in high-fidelity CFD of diffuser-augmented wind turbines

This study presents a novel computational fluid dynamics (CFD) model for accurate and efficient simulation of diffuser-augmented wind turbines (DAWTs). We extend the conventional actuator line (AL) methodology by introducing a pressure-based actuator line (p-AL) model that represents diffuser structures through a body-force distribution derived from their surface-pressure fields. This pressure-derived forcing enables the diffuser’s aerodynamic influence to be captured without explicitly resolving its geometry. The proposed p-AL diffuser model is implemented as a plugin for PyFR, a high-order flux-reconstruction CFD solver. Validation is carried out for two translating-wing configurations and a canonical diffuser case, demonstrating reliable prediction of the diffuser-induced velocity augmentation. Subsequently, a DAWT simulation is performed to evaluate the model’s performance in a realistic turbine environment. The results show that the p-AL model accurately reproduces diffuser effects while reducing computational cost significantly. For the single DAWT case, the proposed model reduces the grid number from 6.83 million in the full-resolved model to 0.87 million cells and decreases the wall-clock time per rotor revolution from 13.79 h to 0.28 h (approximately 98% reduction). Owing to its flexible parameterization, the model can be adapted to a wide range of diffuser geometries. These findings indicate that the pressure-based actuator line framework offers a practical and efficient tool for high-fidelity analysis and design optimization of diffuser-augmented wind turbines. • A pressure-based actuator line (p-AL) model is proposed for representing diffuser structures in DAWTs. • The p-AL formulation reproduces diffuser-induced aerodynamic effects more accurately than conventional AL and AAL models. • The model achieves a substantial reduction in computational cost while maintaining high prediction accuracy. • The p-AL approach reliably predicts wake characteristics and diffuser–rotor interactions in DAWT configurations. • The method is implemented as a PyFR plugin and can be extended to various diffuser geometries through parameter calibration.