S E M I N A R IDepartament d'Astronomia i Astrofísica
Universitat de València
Large Scale Features of Rotating Incompressible Hydrodynamics
Carmen Molina Paris
Mathematical Institute, University of Warwick, UK
Seminari del Departament d'Astronomia i
Dimarts 30 octubre 2001
The large distance and long-time features of a randomly forced incompressible unbounded rotating viscous fluid are examined in perturbation theory. We find there are two physically distinct contributions to the effective viscosity at first order in the noise amplitude. The effective viscosity tensor is the sum of the symmetric and isotropic part plus a particular anti-symmetric and anisotropic contribution. The former contribution serves to "renormalize" the isotropic molecular viscosity, and is independent of the fluid angular velocity, while the latter contribution leads to a new large scale non-dissipative "effective" axial-force proportional to the fluid angular velocity in the slow-rotation regime. This effective force does no net work, is non-dissipative and affects neither the spectral energy density nor the scale-by-scale energy budget. On the other hand, the anisotropic viscosity does alter both the phase and group velocity of plane inertial waves propagating in a rotating fluid.