论文标题
开普勒磁盘中噪声的流体动力不稳定性与磁化不稳定之间的竞争
The competition between the hydrodynamic instability from noise and magnetorotational instability in the Keplerian disks
论文作者
论文摘要
我们冒险进行磁化不稳定性（MRI）（MRI）的生长速率与在局部开普勒积分流中有额外力的情况下的生长速率之间的比较。在旋转，磁场和额外力的存在下，Orr-Sommerfeld和Squire方程描述了基础模型，具有非零均值的合理噪声。我们使用Wentzel-Kramers-Brillouin（WKB）近似获得MRI，而无需额外的力来纯粹的垂直磁场和扰动的垂直波形。预计，MRI在磁场范围内有效，该磁场的变化取决于扰动波形幅度。接下来，为了检查噪声对增长率的影响，已经获得了四分之一的分散关系。在这四种增长率的解决方案中，磁场MRI活性区域中噪声消失的噪声平均值的限制降低到MRI增长率的解决方案中，主要由MRI主导。但是，在MRI无活性区域中，在存在噪声的情况下，溶液证明是不稳定的，几乎与磁场无关。另一个与前一个的增长率几乎是互补的，它导致稳定性的稳定性在消失的噪声极限处。其余两个增长率与消失磁场极限的流体动力学生长速率相对应，与MRI生长速率完全不同。更有趣的是，后者的增长率大于MRI的增长率。如果我们考虑粘度，则增长率会根据雷诺数的数量降低。
We venture for the comparison between growth rates for magnetorotational instability (MRI) and hydrodynamics instability in the presence of an extra force in the local Keplerian accretion flow. The underlying model is described by the Orr-Sommerfeld and Squire equations in the presence of rotation, magnetic field and an extra force, plausibly noise with a nonzero mean. We obtain MRI using Wentzel-Kramers-Brillouin (WKB) approximation without extra force for purely vertical magnetic field and vertical wavevector of the perturbations. Expectedly, MRI is active within a range of magnetic field, which changes depending on the perturbation wavevector magnitude. Next, to check the effect of noise on the growth rates, a quartic dispersion relation has been obtained. Among those four solutions for growth rate, the one that reduces to MRI growth rate at the limit of vanishing mean of noise in the MRI active region of the magnetic field, is mostly dominated by MRI. However, in MRI inactive region, in the presence of noise the solution turns out to be unstable, which are almost independent of the magnetic field. Another growth rate, which is almost complementary to the previous one, leads to stability at the limit of vanishing noise. The remaining two growth rates, which correspond to the hydrodynamical growth rates at the limit of the vanishing magnetic field, are completely different from the MRI growth rate. More interestingly, the latter growth rates are larger than that of the MRI. If we consider viscosity, the growth rates decrease depending on the Reynolds number.
