Unstructured overset incompressible computational fluid dynamics for unsteady wind turbine simulations

Overset computational fluid dynamics (CFD) methods are the most sophisticated methods currently available to predict the unsteady motion of wind turbine blades without the need for additional simplifications or restrictions on the turbine operational conditions. An unstructured implementation of the governing equations of motion permits rapid modeling of the salient components, such as nacelles, towers and other localized obstructions of interest. A time-accurate incompressible formulation accelerates the convergence of the solution, in addition to eliminating the need for low-Mach number preconditioning, which can be problematic and computationally expensive for time-accurate simulations. The use of a hybrid Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/LES) turbulence method is observed to improve the prediction and extent of separation, as well as integrated performance variables for stalled rotors under fully turbulent conditions. Copyright (c) 2012 John Wiley & Sons, Ltd.