Coupled Ostrovsky equations for internal waves in a shear flow
  In the context of fluid flows, the coupled Ostrovsky equations arise when two distinct linear long wave modes have nearly coincident phase speeds in the presence of background rotation. In this paper, nonlinear waves in a stratified fluid in the presence of shear flow are investigated both analytically, using techniques from asymptotic perturbation theory, and through numerical simulations. The dispersion relation of the system, based on a three-layer model of a stratified shear flow, reveals various dynamical behaviours, including the existence of unsteady and steady envelope wave packets. 
A. Alias, R.H.J. Grimshaw, K.R. Khusnutdinova
nlin.PS physics.ao-ph physics.flu-dyn