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题名	行星内部对流和较差转动研究
作者	冯天厚
学位类别	博士
答辩日期	2007-06-09
授予单位	中国科学院上海天文台
授予地点	上海天文台
导师	廖新浩
关键词	快速旋转 行星内部 对流 较差旋转 准地转流 数值模拟
其他题名	Studies on convection instability and differential rotation in planetary interior: quasi-geostrophic approximation
中文摘要	The rapid development of space exploration makes planet dynamics become one of the most active research fields. Understanding the dynamics of the planets is very important for the astrophysics and geophysics. People want to know more detail process of the birth of the magnetic field, the dynamics of the fluid core and the atmosphere, so we can know the evolution of the solar system. In this paper we aimed at the convection and the different rotation in the planetary interior. Our works summarized as follows are based on the quasi-greostrophysic approximation model: 1. We model a rapidly rotating stellar convection zone by a large-gap spherical annulus using a two-dimensional quasi-geostrophic approximation incorporating full spherical geometry and the equation of mass conservation. It is demonstrated that the primary features of thermal instabilities in rapidly rotating spheres or sphere shells are quantitatively captures by large-gap spherical annuluses using the new quasi-geostrophic approximation. 2. Introduced a domain decomposition method suitable the massively parallel computers into the numerical simulation. It can help us improving the efficiency of the parallel. Investigated the results of numerical simulations of convection for planetary core, giant planets atmosphere and extra solar synchronized planets. For the weakly nonlinear convection, the results of simulation support the multi-layer-wave structure first suggested in an analytical model for Jovian atmosphere by Busse(1976). When the nonlinear effect and the corresponding Reynolds stresses become sufficiently large, the mean flow becomes prevailing: the strongly nonlinear flow, dominated by the spatially regular axisymmetric flow, gains the spatial regularity lost in mildly nonlinear convection. 3 Saturation and temporal variation of the mean zonal flow in rapidly rotating quasi-geostrophic spherical systems are investigated. Convective instabilities generate highly coherent small-scale eddies which feed energy into the mean flow via the inverse cascade mechanism. We show that this inverse cascade causes a continual piling up of energy in the mean flow which, in turn, strongly stabilizes the system and hence dramatically reduces the amplitude of the eddies, leading to the reduction and saturation of the mean flow. This implies that a steady state for the fast equatorial zonal jets on giant planets cannot exist.
英文摘要	随着国际深空探测计划的不断实施，行星科学引起了国际天文学和地球科学界的极大关注，人们期望深入研究行星演化过程中诸如磁场是如何产生的、液态核和大气的动力学性质等，以逐步加深人们对太阳系演化的理解。 文章中选用准地转流近似模型，利用有限差分方法集中讨论快速旋转行星内部对流和较差转动问题。本文中主要进行了以下一些方面的研究工作： 1、针对快速旋转行星流体基本展现二维运动基本特征，提取动力学方程中的主要项，建立了一个能较好反映行星内部对流的二维行星准地转流模型，并对线性问题进行了详细的理论分析，给出了对流和较差转动的基本物理形态； 2、采用区域分解的思想，对非线性问题编写了一套高效的并行差分数值模拟软件，在此基础上，分别数值模拟了地球液态外核、木星大气以及太阳系外飞马座51号b-型行星的流体动力学过程，发现它们具有一个共同的动力学特征：当非线性效应弱时，系统基本呈现小尺度对流模式；当非线性效应强时，一些小尺度对流胞会将其能量转移到带状环流，系统主要呈现大尺度平均流模式，此时较差转动特征显著，这与实际观测到的现象相符。 3、基于二维准地转流模型，首次清楚揭示了行星带状环流产生、维持以及变化的动力学过程：热不稳定性产生小尺度对流胞，由于Coriolis力的作用使其不断将能量输送到具有减弱热输送作用的大尺度带状环流，一定时间后热对流接近停止，而粘滞效应逐步损耗带状环流的能量，从而系统的热输送逐步加强，开始新的热不稳定。此过程说明，带状环流随时间是变化的，这与深空探测结构相符。
语种	中文
公开日期	2011-07-01
页码	133
内容类型	学位论文
源URL	[http://119.78.226.72//handle/331011/14612]
专题	上海天文台_中国科学院上海天文台学位论文
推荐引用方式 GB/T 7714	冯天厚. 行星内部对流和较差转动研究[D]. 上海天文台. 中国科学院上海天文台. 2007.

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