Nonlocal-local multimode bifurcation in turbulence

It is shown that a mechanism of energy redistribution and dissipation by the inertial waves can be effectively utilized in isotropic turbulence at small Reynolds numbers (when the nonlocal interactions are the dominating ones). This mechanism totally suppresses the local interactions (cascades) in isotropic turbulence at the Taylor-scale based Reynolds number $R_{\lambda} < 10^2$. This value of $R_{\lambda}$ (that can be considered as a bifurcation value at which the local regime emerges from the nonlocal one in isotropic turbulence) is in agreement with recent direct numerical simulations data. Applicability of this approach to channel flows is also briefly discussed. A theory of multimode bifurcations has been developed in order to explain anomalous (in comparison with the Landau-Hopf bifurcations) properties of the nonlocal-local bifurcation in isotropic turbulence.