Uniform distortion of a heated turbulent wake

Abstract

A slightly heated, cylinder-generated turbulent wake subjected to a constant and uniform rate of strain has been investigated by means of digital sampling and processing techniques. Statistical properties of the interface separating turbulent fluid and contiguous non-turbulent fluid, and of the temperature and streamwise velocity fields have been obtained. The interface statistics show no evidence of the periodic interface motion suggested by several workers. Rather, they indicate that the interface position may be treated as a stationary Gaussian random variable in both the pre-strain region and the strain region. These results are consistent with the view that the entrainment of non-turbulent fluid occurs essentially by viscous action of the interface. The temperature and velocity data establish that there is an abrupt change of the temperature across the interface, whereas the velocity varies gradually. The temperature results suggest that the fronts of the large-scale turbulent bulges are, on the average, sharper than the backs, the implication being that more of the entrainment occurs in these latter regions.