径向粘滞力对薄盘稳定性的影响

在吸积盘内由于吸积物质的径向运动，盘内物质间沿径向的粘滞力将会对盘的性质产生一定影响。本计算了等温吸积盘中（考虑径向粘滞力）的不稳定性问题，对所求得的色散方程的分析表明，径向粘滞力将使吸积盘趋向稳定。本还对径向粘滞力对盘的稳定性的影响作了物理解释，并发现径向粘滞力的引入不会引入新的稳定或不稳定模式。     

对等温,有磁薄吸积盘脉动不稳定性的多因素影响

本从磁流体动力学方程组出发，用微扰法得出等温有磁薄吸积盘径向脉动不稳定性的色散方程，详细讨论了磁场、径向粘滞力和因果性修正的α型粘滞对吸积盘不稳定性的影响。我们的结论是：磁场是一种在全盘区域起作用的非稳因素，它能影响粘滞模式的不稳定性和两种声波模式的增长率。径向粘滞力是一种在全盘区域起作致稳因素，它主要影响两种声波模式的不稳定性。α型粘滞的因果性修正主要在盘内区起作用，它对吸积盘的不稳定性影响较     

对等温、有磁薄吸积盘脉动不稳定性的多因素影响

本文从磁流体动力学方程组出发，用微扰法得出等温有磁薄吸积盘径向脉动不稳定性的色散方程，详细讨论了磁场、径向粘滞力和因果性修正的α型粘滞对吸积盘不稳定性的影响．我们的结论是：磁场是一种在全盘区域起作用的非稳因素，它能影响粘滞模式的不稳定性和两种声波模式（O－mode和Ⅰ－mode）的增长率．径向粘滞力是一种在全盘区域起作用的致稳因素，它主要影响两种声波模式的不稳定性．α型粘滞的因果性修正主要在盘内区起作用，它对吸积盘的不稳定性影响较为复杂：对粘滞模式和无磁盘的Ⅰ-mode，它表现为致稳因素，而对O－mode和有磁盘的两种声波模式，则表现为非稳因素．     

含平流双温吸积盘的振荡不稳定性研究

从流体动力学方程出发,用微扰法得出含平流双温吸积盘的径向、环向不稳定性的色散方程．并对平流和径向粘滞力对双温吸积盘的影响进行了较详细的讨论．结果表明：平流和径向粘滞力对声模有较大的影响,且不改变粘滞模和热模的稳定性质．而环向扰动对吸积盘的各种模有着较明显的作用．这一模型有利于解释活动天体的周期和准周期光变现象．     

含平流双温吸积盘的振荡不稳定性研究

从流体动力学方程出发,用微扰法得出含平流双温吸积盘的径向,环向不稳定性的色散方程,并对平流和径向粘滞力对双温吸积盘的影响进行了较详细的讨论。结果表明：平流和径向粘滞力对声模有较大的影响,且不改变粘滞模和热模的稳定性质。而环向扰动对吸积盘的各种模有着较明显的作用,这一模型有利于解释活动天体的周期和准周期光变现象。     

吸积盘整体结构的统一描述

在考虑径向对流和不同光学厚度的基础上，我们采用一般的辐射致冷假设；在统一的框架内考察了吸积盘的整体结构．对α模型，我们发现在不同的盘区存在不同的整体结构．在吸积率较低时，存在三种类型解：光学厚的局部辐射致冷解；光学薄的局部致冷解；光学薄的对流致冷解．这些解在盘内较大范围内都存在且互不交叉．但在吸积率较高和粘滞系数较大时，两种局部致冷解会相互交叉，而对流为主的解在所有盘区都稳定存在．另一方面，在吸积率较高和粘滞系数较小时，两种光学薄解会相互交叉，而光学厚和局部致冷为主的解在所有盘区都存在．     

吸积盘整体结构的统一描述

在考虑径向对流和不同光学厚度的基础上，我们采用一般的辐射冷假设，在统一的框架内考察了吸积盘的整体结构，对α模型，我们发现在不同盘区在不同的整体结构，在吸积率较低时，存在三种类型解，光学厚的局部辐射冷解，光学薄的局部致冷解，光学薄的对流致冷解，这些解在盘内较大范围内都存在且互不交叉，但在吸积率较高和粘滞系数较大时，两种局部致冷解会相互交叉，而对流为主的解在所有盘区都稳定存在，另一方面，在吸积率较高和     

修正的粘滞律及有磁吸积盘的稳定性研究

本文采用修正的粘滞定律及磁流体力学研究了薄吸积盘内区及外区的稳定性问题。运用微扰方法导出了色散方程，分析了四种情况下吸积盘的不稳定性，结果表明：在同时考虑磁场和修正的粘滞律时，吸积盘中存在着三种振荡模式，其中粘滞模式总是稳定的，磁声速模式（包括向里、向外传播两种模式）通常是不稳定的。这些结果为解释ＢＬ Ｌａｃ天体、Ｓｅｙｆｅｒｔ星系、类星体等活动星系核的光变现象提供了理论依据。     

吸积盘物理：稳定性和振动

研究了环绕致密天体的吸积盘的稳定性质和振动模式。特别关注了在热致和粘滞扰动作用下稳定的对流起支配作用的盘外流。还研究了相对论性吸积盘的振动模式。一些在盘内的捕获的，非衰减的模式也许可以用来解释X射线双星和活动星系核中所观测到的准周期振动。     

黑洞附近吸积流的稳定性研究

本文采用了多方物态方程ｐ＝ｋρ＾（１＋１／ｎ）研究了在黑洞附近跨声速α吸积盘的径向线性稳定性，在导出扰动色散关系时考虑了吸积流的径向运动速度，结果表明粘滞系数α存在一上限αｃ，当α＞αｃ时，吸积流是不稳定的，αｃ与多方指数ｎ及吸积流的径向速度ｖｒ有关。     

The stability of an isothermal,magnetized and causally limited viscosity accretion disk

The stability of an isothermal, magnetized and causally limited viscosity accretion disk is examined in this paper. We find that the viscous modes are always stable throughout the disk, and the magneto-acoustic modes are pulsationally unstable. The results show that the Mach numbers do effect the instabilities of the disk and the magnetic field enhances the instability property of the radial oscillation. Our results are useful for understanding the time variations of AGN.     

原太阳吸积盘结构

计算了粘滞演化阶段原太阳吸积盘结构。采用稳态标准吸积盘模型来描述盘中湍动粘滞；忽略其径向能量传输，将垂直结构作为一维问题处理。假设盘作Keplerian较差旋转，处于流体力学平衡和局域热平衡，盘由粘滞耗散加热，能量通过对流和辐射向外传输。结果表明，对温度敏感的不透明度是决定盘结构的重要因素；原太阳吸积盘为冷的薄盘，盘中热对流不稳定性由外而内，由上而下地终结；行星的形成应首先开始于对流终结的区域。     

Angular momentum transport in quasi-Keplerian accretion disks

We reexamine arguments advanced by Hayashi & Matsuda (2001), who claim that several simple, physically motivated derivations based on mean free path theory for calculating the viscous torque in a quasi-Keplerian accretion disk yield results that are inconsistent with the generally accepted model. If correct, the ideas proposed by Hayashi & Matsuda would radically alter our understanding of the nature of the angular momentum transport in the disk, which is a central feature of accretion disk theory. However, in this paper we point out several fallacies in their arguments and show that there indeed exists a simple derivation based on mean free path theory that yields an expression for the viscous torque that is proportional to the radial derivative of the angular velocity in the accretion disk, as expected. The derivation is based on the analysis of the epicyclic motion of gas parcels in adjacent eddies in the disk.     

The Radial-Azimuthal Instability of Gas-Pressure-Dominated Accretion Disk with Advection

The radial-azimuthal instability of gas-pressure-dominated accretion disk with advection is examined in this paper. We find that the including of very little advection has significant effects on two acoustic modes, which are no longer complex conjugates of each other. They increase the instability of the O-mode and damp that of the I-mode. We also find that when the azimuthal perturbations are considered, the stability properties of disk are different from that in pure radial perturbation case. The increase of azimuthal wave number will stabilize the acoustic modes but make the viscous mode more unstable and does not change the thermal mode very much for optically thin disk. The I-mode is more stable. The O-mode, viscous mode and thermal mode tend to become more unstable with the increase of azimuthal perturbation wavenumber for optically thick disk. For a geometrically slim, advection-dominated disk, the increasing of azimuthal perturbations make thermal mode more unstable and acoustic mode more stable. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the formation of protostellar disks

An analysis is presented of the hydrodynamic aspects of the growth of protostellar disks from the accretion (or collapse) of a rotating gas cloud. The size, mass, and radiative properties of protostellar disks are determined by the distribution of mass and angular momentum in the clouds from which they are formed, as well as from the dissipative processes within the disks themselves. The angular momentum of the infalling cloud is redistributed by the action of turbulent viscosity on a shear layer near the surface of the disk (downstream of the accretion shock) and on the radial shear across cylindrical surfaces parallel to the rotation axis. The fraction of gas that is fed into a central core (protostar) during accretion depends on the ratio of the rate of viscous diffusion of angular momentum to the accretion rate; rapid viscous diffusion (or a low accretion rate) promotes a large core-to-disk mass ratio. The continuum radiation spectrum of a highly viscous disk is similar to that of a steady-state accretion disk without mass addition. It is possible to construct models of the primitive solar nebula as an accretion disk, formed by the collapse of a slowly rotating protostellar cloud, and containing the minimum mass required to account for the planets. Other models with more massive disks are also possible.     

Approximate rotation curve solutions for the evolution of a viscous protogalactic disk

The problem of evolution of viscous protogalactic disks is examined. A modification of traditional turbulent viscosity theory is proposed which is based on the premise that the eddies are so small and numerous that each eddy can be considered to be large molecule. The radial flow term is omitted from the viscosity equation to make it tractable, and the radial flow is later reintroduced via the requirement of gravitational balance within the disk. The main result is a family of rotation curves that, as the system evolves, serially reproduces most types of observed rotation curves. With the use of Seiden's star formation theory, the present model produces an exponential-like luminosity profile whenever stars form and the viscous action ceases.Los Alamos National Laboratory is operated by the University of California for U.S. Dept. of Energy under contract W-7405-ENG-36.     

On the radial distributions of molecular clouds in galaxies

The dynamics of the interstellar gas (the IS gas) driven by the viscous torque of a system of giant molecular clouds (the MC gas) is considered with the infinitesimally thin disk layer approximation. The flow explains the radial distributions of molecules observed in galaxies.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–26 October, 1984.     

Self‐similar evolutionary solutions for an accreting magneto‐fluid around a compact object with finite electrical conductivity

In this paper, we investigate the time evolution of an accreting magneto‐fluid with finite conductivity. For the case of a thin disk, the fluid equations along with Maxwell's equations are derived in a simplified, one‐dimensional model that neglects the latitudinal dependence of the flow. The finite electrical conductivity of the plasma is taken into account by Ohm's law; however, the shear viscous stress is neglected, as well as the self‐gravity of the disk. In order to solve the integrated equations that govern the dynamical behaviour of the magneto‐fluid, we have used a self‐similar solution. We introduce two dimensionless variables, S₀ and ε_ϱ, which represent the size of the electrical conductivity and the density behaviour with time, respectively. The effect of each of these on the structure of the disk is studied. While the pressure is obtained simply by solving an ordinary differential equation, the density, the magnetic field, the radial velocity, and the rotational velocity are presented analytically. The solutions show that the S0 and ε_ϱ parameters affect the radial thickness of the disk. Also, radial velocity and gas pressure are more sensitive to the electrical conductivity in the inner regions of disk. Moreover, the parameter ε_ϱ has a more significant effect on the physical quantities for small radii. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)