OCCURRENCE OF INTERMITTENCY IN A LAMINAR-TURBULENT TRANSITION IN A PLANE COUETTE FLOW
Keywords:Laminar-turbulent transition. Intermittency. Stable boundary layer. Large eddy simulation.
The transition from laminar-turbulent flow regime is important in most of the fluid mechanics application areas. In the planetary boundary layer (PBL), the flow is predominantly turbulent. However, shortly after sunset, the incidence of solar radiation ceases and the surface begins to lose heat through the emission of long-wave, yielding in a thermical stratified stable boundary layer (SBL), where turbulence can be suppressed in almost all scales. Under these conditions the production of turbulence is predominantly mechanical, and at nights with strong stratification, the turbulent activity is reduced by several orders of magnitude and can rise abruptly in unpredictable ways, giving origin to a phenomenon known as global intermittency. The globla intermittency is a phenomenon that occurs in the transition flow in the PBL, similarly to intermittency which occurs in the laminar-turbulent transition. Thus, this work aims to develop a numerical experiment to reproduce the laminar-turbulent transition in a thermally stratified Couette flow, using a large eddy simulation model. The simulations show that for a certain range of parameters during the transition laminar-turbulent, turbulence appeared intermittently in the flow.
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