The fully nonlinear stage of two dimensional Poiseuile flow undergoes a limit cycle bifurcation, whose detailed mechanism is studied using full numerical simulations of simple, spatially periodic cases. It is also shown that this mechanism, a periodic ejection from the wall layer, underlies the production of turbulence in more complicated two dimensional situations. Vorticity ejections are also present in the sublayer of three dimensional channels. Their behaviour is studied briefly in three dimensional simulations. A simplified model system is then proposed and studied. There are important differences between the two ejections mechanisms, due to the presence of three dimensional vorticity
The fully nonlinear stage of two dimensional Poiseuile flow undergoes a limit cycle bifurcation, whose detailed mechanism is studied using full numerical simulations of simple, spatially periodic cases. It is also shown that this mechanism, a periodic ejection from the wall layer, underlies the production of turbulence in more complicated two dimensional situations. Vorticity ejections are also present in the sublayer of three dimensional channels. Their behaviour is studied briefly in three dimensional simulations. A simplified model system is then proposed and studied. There are important differences between the two ejections mechanisms, due to the presence of three dimensional vorticity Read More
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