Helicity Spectra and Dissipation

Both dissipation of helicity and it spectrum we are study on the basis of asymptotic model. Introduction into model dependence of angle between turbulent components vorticity and velocity on the governing parameters leads to the spectra of helicity observed experimentally and obtained by DNS model computations by various authors. At the same time, it settles the problem of helicity dissipation divergence with growing Reynolds number

On the escape of low-frequency waves from magnetospheres of neutron stars

We study the nonlinear decay of the fast magnetosonic into the Alfv\'en waves in relativistic force-free magnetohydrodynamics. The work has been motivated by models of pulsar radio emission and fast radio bursts (FRBs), in which the emission is generated in neutron star magnetospheres at conditions when not only the Larmor but also the plasma frequencies significantly exceed the radiation frequency. The decay process places limits on the source luminosity in these models. We estimated the decay rate and showed that the phase volume of Alfv\'en waves available for the decay of an fms wave is infinite. Therefore the energy of fms waves could be completely transferred to the small-scale Alfv\'en waves not via a cascade, as in the Kolmogorov turbulence, but directly. Our results explain the anomalously low radio efficiency of the Crab pulsar and show that FRBs could not be produced well within magnetar magnetospheres.Comment: ApJ, in pres

Large- and small-scale turbulent spectra in MHD and atmospheric flows

In the present review we discuss certain studies of large- and small-scale turbulent spectra in MHD and atmospheric flows performed by S. S. Moiseev and his co-authors during the last years of his life and continued by his co-authors after he passed away. It is shown that many ideas developed in these works have not lost their novelty and urgency until now, and can form the basis of future studies in this field