非磁化吸积盘中的粘滞性和朗缪尔波湍动应力

VISCOSITY AND LANGMUIR WAVE-TURBULENCE STRESS IN UNMAGNETIZED ACCRETION DISKS

粘滞性问题一直是吸积盘理论中十分重要而又难以解决的一个基本理论问题．最近，Balbus和Hawley建议在磁化吸积盘中存在一种局域的磁流体剪切不稳定性机制，它能导致磁化吸积盘中有效的角动量转移，从而可以部分地解决磁化吸积盘中的粘滞性问题．但是Balbus－Hawley机制对非磁化吸积盘仍然是无效的．在本文中，我们研究了一种非磁化吸积盘模型，其中粘滞性机制起源于等离子体朗缪尔波湍动应力，并与标准a吸积盘模型中起源于流体或磁流体湍流的雷诺应力的粘滞性机制进行了比较．结果表明等离子体朗缪尔波湍动应力不仅对非磁化吸积盘中粘滞性的起源有重要的贡献，而且有可能是比流体湍流或磁流体湍流的雷诺应力更加有效的粘滞性起源的物理机制．

The viscosity is a basic problem which is very imPOrtant and hard to resolve inthe accretion disk theory. Recendy, Balbus and Hawley proPOsed that a poweral local shear instability in magnetized accretion disks is very likely to lead to generic and efficient angular momentum transport, thereby resolving a crucial theoretical puzzle. However, such an instability mechanism cannot work in unmagnetized ascretion disks.A model of unmagnehzed accretion disks in which the viscosity originates from the Langmuir wave-turbulence stress is presented in thes paper, and is compared with the standard a accretion disk model. The results show that the present wave-turbulence seems to be a more efficient viscosity mechanism for unmagnetized accretion disks than the flow-turbulence in the contex of the a model.