A test of gradient transport and its generalization
Abstract
It is pointed out that virtually all the 'classical turbulent theories' model turbulent transport of momentum, heat, or a passive contaminant by linear mean gradient models. In this connection, a recurring concern has been voiced regarding the general conditions for the validity of the gradient transport models (GTM). One of the major goals of the present investigation is related to a determination of the reasons for the (apparent) success of the GTMs. The investigation is almost exclusively concerned with the turbulent heat transport. In the homogeneous shear flows examined, the length scale characteristic of the eddies most effective in transporting heat were found to be small compared with the integral scale of turbulence, or the scale of inhomogeneity of the temperature field. It should, therefore, cause no surprise that the GTM works as well as it does. However, it was found that the GTM cannot handle inhomogeneous flows well and none of the generalizations of the GTM appears to be adequate.
- Publication:
-
Turbulent Shear Flows 3
- Pub Date:
- 1982
- Bibcode:
- 1982tsfi.symp...96S
- Keywords:
-
- Transport Theory;
- Turbulent Flow;
- Circular Cylinders;
- Gradients;
- Shear Flow;
- Temperature Distribution;
- Turbulent Heat Transfer;
- Velocity Distribution;
- Fluid Mechanics and Heat Transfer