Numerical simulation studies of laminar-turbulent transition in the plane channel
Laminar-turbulent transition in the plane channel was studied via direct numerical simulation of the Navier-Stokes equations. The study is the first to allow both the subharmonic and fundamental modes to grow from an initial state of random noise. The subharmonic (Herbert-type) modes are the dominant structures for small amplitudes of the 2D wave while fundamental (Klebanoff-type) modes are more important for large-amplitude 2D waves. Wind-tunnel experiments in the plane channel do not show evidence of the Herbert modes unless they are forced with a subharmonic disturbance. The author hypothesized that this is due to the presence of streamwise vortices in the wind tunnel and included streamwise vortices in the simulations. These vortices produce spanwise variations in the streamwise velocity which are quite similar to those measured in experiments. The inclusion of these vortices changes the dominant mode from the Herbert type to the Klebanoff type. To help in the analysis of transitional flows, the author studied how the intermodal energy-transfer rates varied across the channel. He also studied transitional flow in the presence of an oscillatory pressure gradient.
- Research Organization:
- Stanford Univ., CA (USA)
- OSTI ID:
- 6697877
- Country of Publication:
- United States
- Language:
- English
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