High-Order CFD Modeling of Rotating Actuator Line Systems

Abstract

High-order computational fluid dynamics (CFD) methods combined with actuator-based blade representations provide an attractive approach for simulating rotating energy systems. In this work, we develop a high-order computational framework that couples the flux reconstruction/correction procedure via reconstruction (FR/CPR) formulation with a rotating actuator line model (ALM). Blade rotation and unsteady aerodynamic forces are implemented through time-dependent source terms applied on a fixed cartesian grid. This approach allows simulations of a fully rotating turbine without using explicit blade geometry. Aerodynamic loads are computed using quasi-steady airfoil data and distributed into the flow field with Gaussian smoothing to maintain numerical stability in the high-order scheme. The framework is tested using a two-bladed vertical-axis wind turbine (VAWT) operating at a low tip speed ratio (TSR). The phase-averaged blade motion and overall load are analyzed to study variations with azimuthal angle. In addition, instantaneous and mean flow fields are examined to describe wake structure and unsteady vortex shedding. Normalized mean wake velocity profiles are used for validation through comparison with experimental measurements and blade-resolved large-eddy simulations (LES) reported in the literature. The results show that the proposed high-order virtual-body framework can reliably capture major blade-loading trends, flow organization, and wake features under strongly unsteady conditions, while maintaining geometric simplicity.