Conditional Second Order Closure for Turbulent Shear Flows.
Annual technical rept. 1 Jul 84-30 Jun 85,
CALIFORNIA UNIV DAVIS DEPT OF MECHANICAL ENGINEERING
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The research work during the first year was concentrated on two areas The foundation of conditional closure schemes in terms of probability density functions pdf and the development of a second order closure including intermittency factor and conditional moments. In the theoretical part dynamics of single and multi-point pdfs for velocity and a scalar variable, that can be used for distinction between turbulent and nonturbulent zones, were considered and methods of closure were investigated. The transport of apparent stress in the nonturblent zone of turbulent shear flows with a free boundary was included in the second order model in terms of their dynamic equations. Conditions governing the effect of the fluctuating interface on mean velocity and apparent stress in both zones were established and closure models were put forward. The resulting second order closure was compared with experiments for several plane shear flows and good agreement was found. Research Objectives The objective of the proposed research project is the development of a second order closure model for conditional moments and the intermittency factor. The foundation of the closure scheme are to be investigated and the resulting model should be applicable to a wide range of turbulent shear flows with free boundaries.
- Statistics and Probability
- Fluid Mechanics