An exploration to the modelling of two-dimensional complex turbulent shear flows
Abstract
Regions with shear-stress and mean-velocity gradients of opposite sign often exist in complex turbulent shear flows. In these cases, the eddy-viscosity hypothesis breaks down. Hinze (1970) attributed this to transportation of mean momentum over distance by the large structures and arrived at a shear-stress expression including the second-order derivatives of the mean velocity. However, he gave correct results only qualitatively. Here, the same expression is investigated further and found to overestimate the shear stress greatly. This means that the flow particles are unlikely to have enough memory of the mean momentum over distance. By assuming that the departure from the eddy-viscosity hypothesis is a result of transportation of shear stress contained in smaller eddies over distance by the large structures, a new shear-stress expression is obtained. The shear-stress estimates so far were in good agreement with experiments.
- Publication:
-
Acta Aeronautica et Astronautica Sinica
- Pub Date:
- January 1987
- Bibcode:
- 1987AcAAS...8...20Z
- Keywords:
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- Computational Fluid Dynamics;
- Flow Deflection;
- Shear Flow;
- Turbulent Flow;
- Two Dimensional Flow;
- Eddy Viscosity;
- Velocity Distribution;
- Fluid Mechanics and Heat Transfer