Abstract
Direct numerical simulations (DNS) of non-rotating and rotating turbulent channel flow were conducted. The data base obtained from these DNS simulations was used to investigate the prominent coherent structures involved in the turbulence generation cycle. Predictions from three theoretical models concerning the formation and evolution of sublayer streaks, three-dimensional hairpin vortices and propagating plane waves were validated using visualizations from the present DNS data. Quadrant analysis was used to determine a phase shift between the fluctuating streamwise and wall-normal velocities as a characteristic of turbulence production in the suction region at a low rotation number.
Highlights
The scientific field of turbulence has posed long-standing challenges to researchers due to the inherent chaotic and irregular motions which define turbulent flows
Using direct numerical simulation (DNS), it is instructive to assess the validity of the theoretical model predictions
The Landahl model qualitatively examined the formation and evolution of sublayers streaks in the turbulence system cycle and used the variable interval time averaging (VITA) method to predict structural characteristics suggested by the theoretical model
Summary
The DNS data base from simulation cases A ( Rob = 0 ), B ( Rob = 0.2 ), C ( Rob = 0.5 ) and D ( Rob = 0.9 ) are examined for effects of rotational forces on turbulence over a wide range of rotation rates. In spanwise-rotating turbulent channel flow, the Coriolis force acts in the wall-normal direction, resulting in asymmetry across the channel and the creation of two distinct flow regimes: the pressure and suction regions. In the pressure region of the channel, secondary flow circulation and high levels of turbulence are present and in the suction region, re-laminarization of the regime results in low levels of turbulence
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