TY - JOUR
T1 - An hydrodynamic shear instability in stratified disks
A1 - Dubrulle,B
A1 - Marie,Louis
A1 - Normand,C
A1 - Richard,D
A1 - Hersant,F
A1 - Zahn,Jp
AD - CEA Saclay, GIT, SPEC, DRECAM,DSM,CNRS,URA 2464, F-91191 Gif Sur Yvette, France.
AD - CEA Saclay, SPHT, DSM, CNRS,URA 2306, F-91191 Gif Sur Yvette, France.
AD - Observ Paris, LUTH, F-92195 Meudon, France.
AD - Inst Theoret Astrophys, D-6900 Heidelberg, Germany.
AD - Observ Paris, LESIA, F-92195 Meudon, France.
UR - https://archimer.ifremer.fr/doc/00253/36469/
DO - 10.1051/0004-6361:200400065
KW - accretion, accretion disks
KW - hydrodynamic
KW - instabilities
KW - turbulence
N2 - We discuss the possibility that astrophysical accretion disks are dynamically unstable to non-axisymmetric disturbances with characteristic scales much smaller than the vertical scale height. The instability is studied using three methods: one based on the energy integral, which allows the determination of a sufficient condition of stability, one using a WKB approach, which allows the determination of the necessary and sufficient condition for instability and a last one by numerical solution. This linear instability occurs in any inviscid stably stratified differential rotating fluid for rigid, stress-free or periodic boundary conditions, provided the angular velocity Omega decreases outwards with radius r. At not too small stratification, its growth rate is a fraction of Omega. The influence of viscous dissipation and thermal diffusivity on the instability is studied numerically, with emphasis on the case when d ln Omega/d ln r = - 3/2 (Keplerian case). Strong stratification and large diffusivity are found to have a stabilizing effect. The corresponding critical stratification and Reynolds number for the onset of the instability in a typical disk are derived. We propose that the spontaneous generation of these linear modes is the source of turbulence in disks, especially in weakly ionized disks.
Y1 - 2005/01
PB - EDP Sciences
JF - Astronomy & Astrophysics
SN - 0004-6361
VL - 429
IS - 1
SP - 1
EP - 13
ID - 36469
ER -