Growth of Hydrodynamic Perturbations in Accretion Disks: Possible Route to Non-Magnetic Turbulence

Abstract

We study the possible origin of hydrodynamic turbulence in cold accretion disks such as those in star-forming systems and quiescent cataclysmic variables. As these systems are expected to have neutral gas, the turbulent viscosity is likely to be hydrodynamic in origin, not magnetohydrodynamic. Therefore MRI will be sluggish or even absent in such disks. Although there are no exponentially growing eigenmodes in a hydrodynamic disk, because of the non-normal nature of the eigenmodes, a large transient growth in the energy is still possible, which may enable the system to switch to a turbulent state. For a Keplerian disk, we estimate that the energy will grow by a factor of 1000 for a Reynolds number close to a million.

4 pages; to appear in the Proceedings of COSPAR Colloquium "Spectra & Timing of Compact X-ray Binaries," January 17-20, 2005, Mumbai, India; prepared on the basis of the talk presented by Mukhopadhyay

References in corpus (5)

• Bypass to Turbulence in Hydrodynamic Accretion: Lagrangian Analysis of Energy Growth
• Bypass to Turbulence in Hydrodynamic Accretion Disks: An Eigenvalue Approach
• On the Phenomenology of Hydrodynamic Shear Turbulence
• On non-linear hydrodynamic instability and enhanced transport in differentially rotating flows
• Hydrodynamic Turbulence in Accretion Disks

Cited by in corpus (5)

• Absolute stability of axisymmetric perturbations in strongly-magnetized collisionless axisymmetric accretion disk plasmas
• Collisionless kinetic regimes for quasi-stationary axisymmetric accretion disc plasmas
• An optimal transient growth of small perturbations in thin gaseous discs
• Subcritical transition to turbulence in accretion disc boundary layer
• Algebraic disturbances and their consequences in rotating channel flow transition