A study on spanwise heat transfer in a turbulent channel flow - eduction of coherent structures by a conditional sampling technique

Coherent structures of temperature fields in the near-wall turbulence (y(+) < 60) were educed by a conditional sampling technique from the DNS data. T reated situation is the fully developed turbulent channel flow for two kind s of temperature fields: (a) the uniform heat Aux assigned on two walls of the channel (UHF) and (b) the constant spanwise mean temperature gradient i mposed on the flow over the whole channel width (STG). Following conclusion s are obtained. (1) Flow and temperature fields around the quasi-streamwise vortex are roughly uniform in the streamwise direction. (2) Temperature di stribution in/around the vortex for UHF and that for STG are similar in sha pe with azimuthal phase difference of about 90<degrees>. (3) Mechanisms for destruction of turbulent heat flux are similar between UHF case and STG ca se. (C) 2001 Elsevier Science Inc. All rights reserved.