Bypass transition to turbulence in plane Couette flow: Non-modal and numerical analyses
Final Report Abstract
The main aim of the project was to consider the dynamical characteristics of homogeneous sheared turbulence in the flow that contains the basic mechanisms of shear flow turbulence, while avoiding the complication of more realistic cases. The investigation of this homogeneous turbulence system allowed us to demonstrate explicitly the scheme of action of the bypass concept. The essential idea of our investigation was the analysis of the dynamics in the wavenumber space (i) to follow directly the action of dynamical characteristics of linear and nonlinear processes, (ii) to grasp nonlinear transverse cascade, NTC and (iii) to reconstruct the course of events responsible for the self-sustenance of turbulence. Specifically, it has been shown that the interplay of NTC with linear phenomena can realize either the positive or negative feedback. In the case of positive feedback, NTC repopulates the perturbation harmonics in k-space where the shear flow induces linear transient growth, i.e. repopulates the harmonics with the potential of transient growth.
Publications
- “Homogeneous shear turbulence – bypass concept via interplay of linear transient growth and nonlinear transverse cascade”. Journal of Physics: Conference Series, Vol 708, 2016, 012001
G. Mamatsashvili, S. Dong, G. Khujadze, G. Chagelishvili, J. Jimenez and H. Foysi
(See online at https://doi.org/10.1088/1742-6596/708/1/012001)
