We study the three-dimensional turbulent Kolmogorov flow, i.e. Navier-Stokes equations forced by a low-single-wave-number sinusoidal force in periodic domain, means of direct numerical simulations. This classical model system is realization anisotropic and non-homogeneous hydrodynamic turbulence. Boussinesq's eddy viscosity linear relation checked found to be approximately valid over half volum...

The solar torsional oscillations are considered as the response of the Reynolds stress to the time-dependent dynamo-induced magnetic eld. This picture is opposite to the so far accepted idea that it is the large-scale Lorentz force which directly drives the temporal variations of the surface rotation proole. Here, the \magnetic quenching" of the components of the Reynolds stress { viscosity ten...