Wall-modeled large-eddy simulations of flow over a Gaussian-shaped bump with a relaminarization sensor

Large-eddy simulations are conducted with an equilibrium shear-stress wall model to investigate the flow over a Gaussian-shaped bump geometry. Spanwise periodic simulation results are compared with Direct Numerical Simulations by Uzun & Malik (2020) and experimental data by Williams et al (2020). We consider configurations at two different Reynolds numbers Re_L=10⁶ and 3.41x10⁶ with a freestream Mach number M=0.2. The flow presents mild separation downstream of the bump apex for both Reynolds numbers, and a region of flow relaminarization around the apex for the lower Reynolds number configuration. Direct application of the wall model in the relaminarization region leads to a significant overprediction of the skin friction. A relaminarization sensor is developed to locally condition the application of the wall model based on simulation flow quantities. The predictive capabilities and robustness of the relaminarization sensor are assessed for both Reynolds numbers, along with previously developed laminar-to-turbulent transition sensors by Bodart & Larsson (2012) and Mettu & Subbareddy (2018). The proposed sensor correctly distinguishes the relaminarization region in the low Re_L case, leading to improved flow predictions.