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  本文關(guān)鍵詞：全球日冕演化的自適應(yīng)數(shù)據(jù)驅(qū)動(dòng)模式和日冕磁場外推　出處：《中國科學(xué)院研究生院（空間科學(xué)與應(yīng)用研究中心）》2011年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 太陽日冕 MHD模擬 CESE格式 自適應(yīng)網(wǎng)格(AMR) 動(dòng)態(tài)演化 磁場外推

【摘要】：太陽日冕是空間天氣事件發(fā)生的上層區(qū),其中豐富的結(jié)構(gòu)及其演化是空間物理研究的重要內(nèi)容.數(shù)據(jù)驅(qū)動(dòng)的日冕模擬,是指在日冕底邊界上連續(xù)時(shí)序地輸入觀測數(shù)據(jù)(如磁場)來驅(qū)動(dòng)日冕數(shù)值模式,以模擬日冕真實(shí)的動(dòng)力學(xué)演化;是研究日冕大尺度結(jié)構(gòu)演變和太陽爆發(fā)活動(dòng)的有力工具.本文側(cè)重于計(jì)算技術(shù)層面,基于時(shí)空守恒數(shù)值格式(CESE)和自適應(yīng)網(wǎng)格方法(AMR),開發(fā)了一個(gè)新型的日冕 太陽風(fēng)自適應(yīng)模式;并聯(lián)合光球磁流輸運(yùn)模型,建立了首個(gè)由時(shí)變光球磁圖驅(qū)動(dòng)的全球日冕動(dòng)態(tài)演化MHD模式. 作用一種新型高效的數(shù)值格式, CESE方法已成功地應(yīng)用于多種空間物理問題的模擬研究.基于一般曲線坐標(biāo)理論,本文通過把物理空間下的主控方程變換到計(jì)算空間并保持守恒形式,首先將CESE格式推廣到了一般曲線坐標(biāo)下.然后借助于并行自適應(yīng)軟件包PARAMESH,并克服了CESE格式和自適應(yīng)網(wǎng)格系統(tǒng)的各種不兼容性(如時(shí)空交錯(cuò)問題,庫朗數(shù)敏感問題等),將一般曲線CESE格式成功實(shí)現(xiàn)于塊狀自適應(yīng)網(wǎng)格上,建立了一個(gè)MHD數(shù)值模擬的新方法AMR-CESE-MHD. 為精確刻畫日冕底部球型邊界面而不引入兩極奇點(diǎn)問題,采用一種基于球坐標(biāo)的重疊型網(wǎng)格(Yin-Yang網(wǎng)格)以克服其他網(wǎng)格系統(tǒng)的各種弱點(diǎn),并利用高精度的插值保證重疊邊界信息相互無障礙的傳遞.自適應(yīng)的日冕 太陽風(fēng)模型即建立于該網(wǎng)格系統(tǒng)和AMR-CESE-MHD方法上.時(shí)變自洽的底面邊界條件基于投影特征線方法和一個(gè)描述光球磁圖演化的模型 表面磁流輸運(yùn)(SFT)模型.SFT模型采用觀測的綜合磁圖作為輸入,能夠很好的再現(xiàn)長達(dá)幾個(gè)月的日面磁流的變化,而且避免了直接采用觀測磁圖而導(dǎo)致的不兼容性.通過模擬長達(dá)三個(gè)太陽自轉(zhuǎn)周的動(dòng)態(tài)演化并與多觀測日冕圖像進(jìn)行比較,展示了該日冕動(dòng)態(tài)模式模擬全球日冕基本結(jié)構(gòu)如冕流,冕洞位置和活動(dòng)區(qū)磁場及其演化的能力. 此外,由于日冕的三維磁場尚不能直接觀測.作為一種替代辦法,磁場外推(重構(gòu))也是研究日冕活動(dòng)的一種重要方法.通過考察外推磁場的拓?fù)浣Y(jié)構(gòu),可以發(fā)掘?qū)е绿柋l(fā)活動(dòng)的不穩(wěn)定磁場位形.本文針對于重構(gòu)日冕磁場的松弛法,提出了一種新的實(shí)現(xiàn)方式.不同于以往的僅求解無力場模型的辦法,我們采用全磁流體模型,并利用簡潔而高效的CESE格式來求解.光球(底面)邊界條件類似于擠壓 松弛(stress-and-relax)方法,使初始的勢場分布逐漸逼近于觀測的矢量磁圖.計(jì)算區(qū)域的其他人工邊界全部采用基于投影特征線方法的無反射邊界條件.我們將這個(gè)方法外推了無力場的兩個(gè)經(jīng)典解析解.結(jié)果證明了方法的有效性并且細(xì)致的分析發(fā)現(xiàn)和目前國際上最好的方法相當(dāng).
[Abstract]:The solar corona is the upper layer of space weather events, in which rich structures and their evolution are important contents of space physics research. It refers to the continuous input of observational data (such as magnetic field) at the bottom boundary of the corona to drive the numerical model of the corona to simulate the real dynamic evolution of the corona. It is a powerful tool for studying the evolution of the coronal large-scale structure and solar burst. This paper focuses on the computational techniques, based on the time-space conservation numerical scheme (CESE) and adaptive grid method (AMRs). A new adaptive model of coronal solar wind is developed. Combined with the optical sphere flux transport model, the first global coronal dynamic evolution MHD model driven by a time-varying optical sphere magnetic map is established. As a new and efficient numerical scheme, the CESE method has been successfully applied to the simulation of various spatial physics problems based on the general curvilinear coordinate theory. In this paper, the main control equation in the physical space is transformed into the computational space and the conservation form is maintained. Firstly, the CESE scheme is extended to the general curvilinear coordinates, and then the parallel adaptive software package PARAMESH is used. It overcomes all kinds of incompatibilities of CESE scheme and adaptive grid system, such as time-space interleaving problem, Current number sensitive problem and so on. The general curve CESE scheme is successfully implemented on the block adaptive grid. A new MHD numerical simulation method, AMR-CESE-MHD, is established. In order to accurately characterize the spherical boundary surface at the bottom of the corona without introducing the bipolar singularities, an overlapping meshes based on spherical coordinates (Yin-Yang mesh) are used to overcome the weaknesses of other grid systems. High precision interpolation is also used to ensure the smooth transmission of overlapping boundary information. Adaptive Corona. The solar wind model is based on the grid system and the AMR-CESE-MHD method. The time-varying self-consistent bottom boundary condition is based on the projection feature line method and a model to describe the evolution of the optical sphere magnetic map. Surface magnetic current transport (. The SFT model SFT model uses the observed synthetic magnetic map as the input. It can reproduce the variation of the helioid flux for several months. In addition, the incompatibility caused by the direct use of observational magnetic maps is avoided. The dynamic evolution of three solar rotation cycles is simulated and compared with the multi-observational coronal images. The ability of the dynamic model to simulate the global coronal basic structures such as coronal current, coronal hole position and magnetic field in the active region and its evolution are demonstrated. In addition, because the three-dimensional magnetic field of the coronal can not be observed directly, as an alternative method, the extrapolation of magnetic field (reconstruction) is also an important method to study the coronal activity. The topological structure of the extrapolation magnetic field is investigated. The unstable magnetic field configuration which leads to the solar burst activity can be discovered. In this paper, a new realization method is proposed for the relaxation method of the reconstructed coronal magnetic field, which is different from the previous method which only solves the model of the force field. We use a magnetic fluid model and a simple and efficient CESE scheme to solve the problem. The boundary conditions of the optical sphere (bottom) are similar to those of the squeeze relaxation stress-and-relaxation method. The distribution of the initial potential field is gradually approaching to the observed vector magnetic map. The other artificial boundaries of the computational region are all based on the non-reflective boundary conditions based on the projection characteristic line method. We extrapolate two of the two fields of the force field by using this method. The results show that the method is effective and the detailed analysis shows that it is comparable to the best method in the world.
【學(xué)位授予單位】：中國科學(xué)院研究生院（空間科學(xué)與應(yīng)用研究中心）
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2011
【分類號(hào)】：P182.62

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

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本文編號(hào)：1430077