The Inertialized Rice Convection Model
The Inertialized Rice Convection Model
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DOI：
10.1029/2019ja026811
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发表时间：
2019-12
期刊：
影响因子：
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通讯作者：
Jian Yang;R. Wolf;F. Toffoletto;S. Sazykin;Wenrui Wang;J. Cui
中科院分区：
文献类型：
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作者：
Jian Yang;R. Wolf;F. Toffoletto;S. Sazykin;Wenrui Wang;J. Cui
赖斯对流模型(RCM)是一个已建立的第一原理物理模型，其中场向电流密度由Vasyliunas方程计算。它的慢流假设忽略了MHD动量方程中的惯性项，这是用RCM来模拟等离子体片中突发性整体流动的一些流体动力学的主要障碍。本文描述了RCM-I，它通过修正场向电流的表达式来近似地在RCM中增加惯性效应。惯性流是在假设每条场线上的质量集中在赤道平面附近的情况下计算出来的。RCM-I结果以两种不同的方式计算磁场：基于静态统计的模型和MHD代码。在这两种情况下，气泡的流动速度都比传统的RCM计算的速度要小得多，也更接近实际。另一个有希望的特征是，注入低熵气泡会产生交换(制动)振荡和浮力波，这些波动和浮力波从原始气泡辐射出去，形成多个流动漩涡。这些特征都不是传统的RCM模拟所能产生的。对比模拟还表明，梯度漂移和曲率漂移对气泡的振荡有很大影响，并有抑制浮力波的趋势。我们还注意到，今后还需要做大量工作，通过将各向异性版本的RCM进行惯性化来进一步改善气压分布，并了解忽略磁层-电离层通信时间的影响。
The Rice Convection Model (RCM) is an established first‐principles physics model in which the field‐aligned current density is computed by the Vasyliunas equation. Its slow‐flow assumption neglects the inertial term in the MHD momentum equation, which is a major obstacle to using the RCM to model some of the fluid dynamics of bursty bulk flows in the plasma sheet. This paper describes the RCM‐I, which represents an effort to approximately add inertial effects in the RCM by correcting the expression for field‐aligned currents. That inertial current is calculated under the assumption that the mass on each field line is concentrated near the equatorial plane. RCM‐I results are presented with magnetic fields calculated in two different ways: A static statistics‐based model and an MHD code. In both cases, the bubble flow velocities are much smaller and more realistic than those calculated from the traditional RCM. An additional promising feature is that the injection of a low‐entropy bubble produces interchange (braking) oscillations and buoyancy waves that radiate away from the original bubble, forming multiple flow vortices. None of these features could be produced by traditional RCM simulations. Comparison simulations also suggest that gradient and curvature drifts have substantial effect on oscillation of bubbles and tend to damp buoyancy waves. We also note that substantial work will be needed in the future to further improve the pressure distribution by inertializing an anisotropic version of the RCM and to understand the effects of neglecting the magnetosphere‐ionosphere communication time.