Pressure anisotropy and small spatial scales induced by velocity shear

Daniele del Sarto (1) , Francesco Pegoraro (2, 3) , Francesco Califano (2, 3)

1 IJL - Institut Jean Lamour
2 Dipartimento di Fisica "E. Fermi"
3 CNISM - Consorzio Nazionale Interuniversitario per le Scienze FIsiche della Materia

By including the full pressure tensor dynamics in a fluid plasma model, we show that a sheared velocity field can provide an effective mechanism that makes the initial isotropic pressure nongyrotropic. This is distinct from the usual gyrotropic anisotropy related to the fluid compressibility and usually accounted for in double-adiabatic models. We determine the time evolution of the pressure agyrotropy and discuss how the propagation of " magnetoelastic perturbations " can affect the pressure tensor anisotropization and its spatial filamentation, which are due to the action of both the magnetic field and the flow strain tensor. We support this analysis with a numerical integration of the nonlinear equations describing the pressure tensor evolution.

Domaines: Physique [physics]

Daniele del Sarto, Francesco Pegoraro, Francesco Califano. Pressure anisotropy and small spatial scales induced by velocity shear. Physical Review E , 2016, 93 (5), pp.53203 - 53203. ⟨10.1103/PhysRevE.93.053203⟩. ⟨hal-01780898⟩