DNS study of turbulent heat transfer in a spanwise rotating square duct

In this paper, direct numerical simulation (DNS) is performed to study the effects of the Coriolis force on turbulent heat transfer within a square duct subjected to spanwise system rotation. In order to investigate the rotation effects on the heat transfer process, a wide range of rotation numbers have been tested. In response to the system rotation, secondary flows appear as large streamwise counterrotating vortices, which interact intensely with the four boundary layers of the square duct and have a significant impact on the statistics of the coupled velocity and temperature fields. It is observed that at sufficiently high rotation numbers, a Taylor-Proudman region appears and the flow approaches a complete laminarization state near the top and side walls. The influence of large organized secondary flows on the turbulent kinetic energy of the velocity field and turbulent scalar energy of the temperature field have been investigated through a spectral analysis. The effects of system rotation on the production of the temperature variance have been examined through a budget analysis of its transport equation.