Turbulent actuation of the inlet flow for a boundary layer with a mild adverse pressure gradient

In this paper, we propose an upstream tripping method for turbulence generation in large-eddy simulation of a boundary layer that separates due to an adverse pressure gradient. High-order spectral-element method is used for the numerical simulation and an arc-type trip is located near the inlet boundary of the configuration with a mild adverse pressure gradient. We investigate how the trip height, position, number as well as the inlet velocity profile affect the downstream flow characteristics. Also, we examine how the resulting turbulent boundary layer separates to form a shear layer. The tripping technique is compared with a previously validated precursor method in terms of computational cost, accuracy and effort. Validation is conducted using a reference experiment in terms of separation and reattachment locations. Instantaneous flowfield and the first- and second-order statistics demonstrate the strong performance of the tripping cases. The results suggested that the tripping method outperforms the precursor approach in both accuracy and computational cost.