Investigation of various solution strategies for the time-spectral method for incompressible, viscous flows

To outline the advantages and disadvantages of the proposed solution strategies the laminar flow around the pitching NACA0012 airfoil was investigated. Moreover, unsteady simulations using first and second order time-stepping techniques were used and the time-spectral results were compared to regular time-stepping approaches. It is shown that the time-spectral implementations solving the whole temporal-spatial system are faster than the regular time-stepping schemes. The efficiency of the time-spectral solver decreases with increasing number of harmonics. Furthermore, with a small number of harmonics the lift coefficient over time is not accurately predicted.