Computation of Complex Terrain Turbulent Flows Using Hybrid Algebraic Structure-Based Models (ASBM) and LES

Abstract

In this work, we revisit the coupling of the Algebraic Structure-Based Model with popular two-equation eddy viscosity models (EVM). We consider both the $v^{2}-f$ model and variants of the $\kappa$-$\omega$ model. Our aim is to explore the role of the EVM in these couplings. Computations of turbulent boundary layer over a flat plate and a fully developed channel flow are initially performed for validation purposes. Then, the case of a 2D steep, smooth hill is considered, for which additional LES computations were performed in order to ascertain the validity of the experimental data. The coupling of the ASBM with the $\kappa$-$\omega$-BSL model (hereafter called ASBM-BSL) showed superior robustness when compared to the ASBM-$v^{2}$-f hybrid model. Moreover, ASBM-BSL captures the size of the recirculation bubble more accurately, and overall yields a noticeable improvement in the prediction of the turbulent statistics in the recirculation region. All models fail to capture the correct shear stress profile at the top of the hill, exhibiting positive, non-realizable values near the wall. The present comparisons reveal a sensitivity of the hybrid closures to the choice of carrier model.

Keywords

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