Geometrical Properties of the Resolved-Scale Velocity and Temperature Fields Predicted using Large-Eddy Simulation |
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Authors: | Jing Yin Bing-Chen Wang Donald J. Bergstrom |
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Affiliation: | 1. Dept. of Mechanical Engineering, Univ. of Saskatchewan, Saskatoon, Saskatchewan, Canada, S7N 5A9 2. Defence R&D Canada—Suffield, STN Main, P.O. Box 4000, Medicine Hat, Alberta, Canada, T1A 8K6
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Abstract: | In this paper, local geometrical properties of the velocity and temperature fields of combined forced and natural convection in a vertical slot are studied using large-eddy simulation based on both numerical and analytical approaches. Previous studies on turbulence geometrical statistics appearing in the literature have primarily focused on either isothermal or isotropic turbulent flows; whereas in this work, we extend the scope of research to investigation of a wall-bounded thermal flow. In particular, we focus on studying the resolved helicity, enstrophy generation, local vortex stretching, and a variety of characteristic geometrical alignment patterns between the resolved velocity, vorticity, temperature gradient, subgrid-scale heat flux and the eigenvectors of the resolved strain rate tensor. In order to quantify the effect of buoyancy on the geometrical properties of the thermal flow field, a systematic comparative analysis has been conducted based on three different flow regimes (i.e., viscous sublayer, buffer layer and logarithmic layer) in both the hot and cold wall regions. The near-wall restriction on the geometrical property of the thermal flow field has been analyzed and some interesting wall-limiting geometrical alignment patterns in the form of Dirac delta functions are also reported. |
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