Deflected wind field over a two-dimensional steep ridge subjected to yawed inflow

Abstract

In this study, large-eddy simulations (LES) are performed to investigate the turbulent wake flow of a two-dimensional ridge with cosine-squared cross-section at four inflow directions, i.e., 0, 15, 30, and 45 degrees. The power law index of the mean velocity profile of the approaching turbulent boundary layer is 0.13. The variations of separation bubble, mean and fluctuating velocities, wind deflection angles, speed-up ratio and power spectra density with inflow angle are systematically investigated. One significant horizontal feature of the flow field is that the yawed inflow deflects further when it encounters the two-dimensional ridge. The yaw angles exhibit strong non-linear relationships with the inflow angle, especially at locations influenced by the separation bubble. The length of the separation bubble projected to the plane perpendicular to the ridge gradually decreases with an increasing inflow angle. Meanwhile, the longitudinal mean velocity above the ridge and the vertical mean velocity near the windward side decrease with a higher inflow angle. A lateral mean velocity emerges and strengthens as the inflow angle increases. In addition, peak frequency in the power spectrum of longitudinal velocity rises with increasing inflow angle, accompanied by higher energy concentrations near the peak frequency.