On the Spiral Roll State in Heat Convection between Non-Rotating   Concentric Double Spherical Boundaries
  The single-arm spiral roll state in the system of Boussinesq fluid confined between non-rotating double concentric spherical boundaries with an opposing temperature gradient previously reported by Zhang et al.(Phys. Rev. E, v66, 055203, 2002) has been numerically investigated in detail. It is presented that the state can exist even in a relatively thicker gap rather than that used in our previous reports as a travelling wave solution with a finite constant angular velocity. 
Takahiro Ninomiya, Keito Konno, Masako Sugihara-Seki, Tomoaki Itano
physics.flu-dyn astro-ph.EP