Reynolds stress closure model for conditional variables
Abstract
Free boundaries of turbulent shear flows show an intermittent character with a sharp interface separating instantaneously turbulent and non-turbulent zones shown by Corrsin and Kistler (1954). Prediction models for turbulent shear flows did not take this intermittent character into account so far. In this paper a second order closure model for turbulent shear flows based on conditional variables (Dopazo (1977)) is presented, that allows prediction of intermittency factor, zone-conditioned mean velocities and Reynolds-stresses. It is based on an earlier closure for intermittency factor, mean velocities and kinetic energy and dissipation rate (Byggstoyl and Kollmann (1981)) which used the concept of turbulent pseudo-viscosity for the turbulent zone. The equations for conditional moments contain explicitly terms accounting for the relative motion of turbulent and non-turbulent zones and the transport of various quantities through it. Some of those terms are non-closed on the second-order level and their closure is discussed. The resulting conditional Reynolds-stress model is evaluated by comparison of calculated properties of various thin shear flows with experimental results.
- Publication:
-
4th Symposium on Turbulent Shear Flows
- Pub Date:
- 1984
- Bibcode:
- 1984stsf.proc...14J
- Keywords:
-
- Computational Fluid Dynamics;
- Reynolds Stress;
- Shear Flow;
- Turbulent Flow;
- Combustible Flow;
- Intermittency;
- Momentum;
- Stress Tensors;
- Fluid Mechanics and Heat Transfer