Large Eddy Simulations of Turbulent Mixing Flows with Negative Buoyancy in a Vertical Channel

by Mr Zonglan Wei

Thursday 19 Nov 2020, 14:00 → 15:00 Europe/Zurich

LSM Webinar (ZOOM ID: 926 749 104 28 PC: 278 636)

Abstract:

The results of Large Eddy Simulations (LES) of a downward wall jet that encounters a upward flow in a vertical rectangular channel are presented. The jet fluid has higher temperature than the opposing stream so that the influence of negative buoyancy force on the physics of mixing process can be investigated. Two sub grid models (SGS) are used to perform the simulations: the dynamic one-equation model and the Wall-Adapting Local Eddy-viscosity (WALE) model. The time-averaged mean velocity field and fluctuation velocity field agree well the experimental data. Due to the lack of detailed information concerning the inlet velocity profiles in the experiment, LES results tend to predict a slightly longer distance of penetration of the jet in all the conditions. Besides the sparse data that the experiment documented, the present LES results also provide an accurate, high-resolution, three-dimensional database of turbulent mixing. The first-order and second-order statistics and budgets of the turbulent fields are analyzed. This information will be used as a guide to derive anisotropic closure models applicable to unsteady Reynolds-averaged Navier–Stokes simulations (URANS) for buoyant flows in complex geometries.