Turbulent Heat Transfer Associated with Coherent Structures in Fully Developed Pipe Flow

Abstract

Turbulent heat flux and Reynolds stress fluctuations in fully developed pipe flow have been measured by employing the combined cold wire and V-shaped hot wire anemometry technique, and then conditionally sampled and averaged. Instantaneous turbulent heat transfer is strongly associated with and dominated by the coherent turbulent structures, and thus the inherent intermittency of turbulent heat transport process is the consequence of the intermittent coherent motion near the wall. Conditionally averaged patterns of velocity, temperature and relevant turbulent heat flux fluctuations are obtained by analyzing the amplitude, mean period and duration of coherent motions. These recognized patterns reveal how the turbulent heat transfer is affected by four distinct types of coherent motions originating in the wall region and extending through a greater of the pipe section.