Beyond oscillating-airfoil theory: a novel spinning-airfoil model for lift-based VAWT aerodynamics

• A new Spinning Airfoil Model (SAM) is proposed for Darrieus turbine analysis. • SAM improves upon existing Oscillating Airfoil Models (OAMs). • CFD results show that SAM achieves high accuracy while reducing computational cost. • SAM offers flexible kinematic configurations for Darrieus simulations. • SAM enables efficient sensitivity studies and underlies dimensionless parameters. Oscillating airfoil models (OAMs) have been widely employed in various applications to analyze flow structures and dynamic stall phenomena. Owing to their kinematic similarity and extensive prior research, these models have also been adopted in Darrieus turbine studies. However, existing OAMs fail to accurately capture the velocity field, flow curvature, and blade–wake interactions in such turbines. To address these shortcomings, this study introduces a new kinematic model, the Spinning Airfoil Model (SAM), which improves upon existing OAMs by refining their pitching and surging functions and incorporating an additional plunging motion. Based on the proposed kinematic model, a CFD model was developed to evaluate its aerodynamic performance compared to a benchmark model and two OAM patterns. Simulation results show that SAM accurately reproduces Darrieus turbine behavior with superior numerical performance. Compared to the benchmark model, it predicts the instantaneous thrust coefficient with a determination factor ( R 2 ) of 99.60 % and the mean thrust coefficient with a relative error of 1.38% over a full cycle. SAM converges in approximately one-sixth of the benchmark time, using 5.3 times smaller domain and 3.6 times fewer mesh elements. By embedding the turbine’s key parameters into the three motion functions, SAM provides a straightforward tool for sensitivity analysis and deeper insight into flow structures and vortex dynamics. It also provides a foundation for defining Darrieus-specific dimensionless parameters to classify performance metrics and support comparative studies under consistent conditions. Moreover, its flexible kinematic configurations enable new approaches in numerical and experimental modeling of Darrieus turbines.