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A direct numerical simulation with turbulent transport of a scalar quantity has been carried out to grasp and understand a laminarization phenomena caused by a pipe rotation. In this study, the Reynolds number, which is based on a bulk velocity and a pipe diameter, was set to be constant; Re_b=5283, and the rotating ratios of a wall velocity to a bulk velocity were set to be 0.5, 1.0, 2.0 and 3.0. A uniform heat‐flux was applied to the wall as a thermal boundary condition. Prandtl number of the working fluid was assumed to be 0.71. The number of computational grids used in this study was 256×128×128 in the z‐, r‐ and ϕ‐ directions, respectively. The turbulent quantities such as the mean flow, temperature fluctuations, turbulent stresses and pressure distribution and the turbulent statistics were obtained. Moreover, the Reynolds stress and the scalar flux budgets were also obtained for each rotating ratio. The turbulent drag decreases with the rotating ratio increase. The reason of this drag reduction can be considered that the additional rotational production terms appear in the azimuthal turbulence component. The contributions of convection and production terms to the radial scalar flux budget and also to the balance with temperature‐pressure gradient term are significant. The dissipation and viscous diffusion terms are negligible in higher rotating ratio.

A direct numerical simulation code with cylindrical geometry has been developed. A direct numerical simulation (DNS) of an impinging round jet into parallel disks is performed for a Reynolds number of 10,000 based on the nozzle exit velocity and the nozzle diameter (D). Mean flow variables, turbulent intensity, pressure distribution and turbulent kinetic energy budgets are obtained at various radial locations. The present DNS results are in fairly good agreement with the two‐dimensional PTV measurements by Nishino and co‐workers in 1996. Some flow features of this impinging round jet regarding a turbulent transition process are discussed.