Abstract
This study is conducted to investigate the dissimilarity between momentum and heat transfer in a turbulent channel flow. In the preceding report, it was shown that the dissimilarity is strongly related to the transverse vortex structure where Reynolds stress can be suppressed by the effect of wall-normal velocity and pressure gradient fluctuation correlation. The dissimilarity is remarkably enhanced in 2-D channel flow in which the turbulent mixing is governed by the transverse vorticity. Here in this report, the time history of Reynolds stress and turbulent heat flux in Lagrangian path of fluid particle is considered from numerical results of 2-D flow. The dissimilarity is strongly dependent on the correlation between time integral of (∂p/∂x) and wall-normal velocity. Then a numerical experiment is carried out to control the 3-D turbulent flow to the 2-D solution based on two kinds of methods for the chaos control proposed by Pyragas. The results show that the 3-D flow is successfully converged with a quite small work of control input to the travelling wave solution of 2-D flow. The drag is reduced more than 70% from the 3-D turbulent flow with the heat transfer reduction of about 50%.
