Three-dimensional turbulent flow and heat transfer characteristics of longitudinal vortices embedded in turbulent boundary layer in bent channels

Abstract

The present study numerically investigated the three-dimensional turbulent flow and heat transfer characteristics of longitudinal vortices embedded in a turbulent boundary layer in a bent channel and examined the effects of a spanwise pressure gradient on the distortion of the turbulent boundary layer. The commercial code (ANSYS Fluent v17.0) was used for the simulation with the Reynolds stress model (RSM) to consider anisotropic effects. The simulation results showed that an asymmetric distortion of the turbulent boundary layers and a substantial change in the vortex shape were caused by the presence of an additional mean shear rate, originated from the spanwise pressure gradient. It was also found that an increase in the spanwise pressure gradient contributed to an enhancement of production of turbulent kinetic energy, resulting in stronger mixing flows. In particular, the Stanton number had an asymmetric distribution mainly in the bent region where the spanwise pressure gradient was dominant.