1203.2630 (Min-Kai Lin)

Rossby wave instability in locally isothermal and polytropic disks: three-dimensional linear calculations    [PDF]

Min-Kai Lin

Numerical calculations of the linear Rossby wave instability (RWI) in global three-dimensional (3D) disks are presented. The linearized fluid equations are solved for vertically stratified, radially structured disks with either a locally isothermal or polytropic equation of state. It is confirmed that the RWI operates in 3D. There is little difference in growth rates between 3D and two-dimensional (2D) calculations. Comparison between 2D and 3D solutions suggest the RWI is fundamentally a 2D instability and that three-dimensional effects, such as vertical motion, to be interpreted as a perturbative consequence of the dominant 2D flow. The vertical flow around co-rotation, where vortex-formation is expected, is examined. In locally isothermal disks the expected vortex center remains in approximate vertical hydrostatic equilibrium. For polytropic disks the vortex center has positive vertical velocity, whose magnitude increases with decreasing polytropic index $n$.

View original: http://arxiv.org/abs/1203.2630