Lognormality in Turbulence Energy Spectra

Magnetohydrodynamic Turbulence: Generalized Energy Spectra

A general framework that incorporates the Iroshnikov-Kraichnan (IK) and Goldreich-Sridhar (GS) phenomenalogies of magnetohydrodynamic (MHD) turbulence is developed. This affords a clarification of the regimes of validity of IK and GS phenomenalogies and hence help resolve some controversies in this problem. Magnetohydrodynamic (MHD) flows that occur naturally (like astrophysical situations) and...

Energy spectra in elasto-inertial turbulence

Large-scale energy spectra in surface quasi-geostrophic turbulence

is studied. The nonlinear transfer of this system conserves the two quadratic quantities Ψ1 = 〈[(−∆) ψ]〉/2 and Ψ2 = 〈[(−∆) ψ]〉/2 (kinetic energy), where 〈·〉 denotes a spatial average. The energy density Ψ2 is bounded and its spectrum Ψ2(k) is shallower than k in the inverse-transfer range. For bounded turbulence, Ψ2(k) in the low-wavenumber region can be bounded by Ck where C is a constant inde...

Large-scale lognormality in turbulence modeled by the Ornstein-Uhlenbeck process.

Lognormality was found experimentally for coarse-grained squared turbulence velocity and velocity increment when the coarsening scale is comparable to the correlation scale of the velocity [Mouri et al., Phys. Fluids 21, 065107 (2009)]. We investigate this large-scale lognormality by using a simple stochastic process with correlation, the Ornstein-Uhlenbeck (OU) process. It is shown that the OU...

Collapse spectra of cloud turbulence

The collapse spectra of cloud turbulence are obtained from the governing equations of the self-gravitating system. The spectra can be used to explain the observed scaling behaviour of the internal velocity dispersions and macrostructural density inhomogeneity in molecular clouds.