Loosely coupled under-resolved LES/RANS simulation augmented by sparse near-wall measurement

Abstract

We investigate scenarios, where only sparse wall shear stress measurements are available, while accurate wall shear stress and velocity profiles are sought. Applying discrete adjoint-based data assimilation, with only near-wall measurements, accurate wall shear stress profiles are achieved at the expense of unrealistic velocity profiles. We therefore add and employ internal reference data generated by performing a relatively cheap hybrid simulation. We modified the dual-mesh hybrid LES/RANS framework recently proposed by Xiao and Jenny (J Comput Phys 231(4):1848–1865, 2012, https://doi.org/10.1016/j.jcp.2011.11.009) by loosely coupling under-resolved LES in the interior with steady RANS near the walls. The framework was developed in OpenFOAM and tested for flow over periodic hills with Re = 10,595. Results show that the devised framework outperforms conventional dual-mesh hybrid LES/RANS and standalone sparse wall-data assimilated RANS models. Graphical abstract Horizontal mean velocity component \(U_{1}\) (top plot) and wall shear stress (friction coefficient \(C_{f}\)) profiles at the lower wall (bottom plot) obtained with S-RANS and assimilation of sparse wall shear stress data