Computation of 3D Hydrodynamic, Hydromagnetic and Dust-Laden Flows in Protoplanetary Disks and Their Roles in Planetesimal and Star Formation

原行星盘中 3D 流体动力、流体磁力和尘埃流动的计算及其在小行星和恒星形成中的作用

• 批准号: 0607836
• 负责人: Philip Marcus
• 金额: $ 28.85万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0607836&HistoricalAwards=false
• 关键词: Computation; 3D; Hydrodynamic; Hydromagnetic; Dust

ABSTRACTThe research to be carried out here centers on the transportation of mass and angularmomentum in protoplanetary disks surrounding young stars. "Turbulence" or "eddyviscosities" have been invoked to solve a variety of problems, including the transport ofangular momentum outward from a disk to allow mass to accrete onto a central protostar,the accumulation of dust to produce planetesimals, and their ability to act as an enhancedviscosity which allows planetesimals or planets to migrate radially in the disk away fromthe regions in which they formed. However, computing the transport of angularmomentum, dust, planetesimals, and planets within a disk using transport rates from"eddy viscosities" may well be incorrect. Here, the sustainability of another process,magnetohydrodynamic turbulence (which is highly dissipative) and its ability to transportangular momentum, will be studied as a function of the disk's ionization. In addition, theinvestigator's previous work has shown that vortices are efficient at transporting angularmomentum. His 3D modeling further indicates that grains can be trapped in these vorticesand concentrated. Using two new codes, one a hybrid particle/gas code and the other atwo-phase flow code in which one phase is the gas and the other is the dust, theaccumulation of dust in the disk's mid-plane, in the vortices that form within a disk, andin the inter-eddy regions of the turbulence will be examined. All of these locations havebeen suggested to be regions where dust concentrates and then undergoes agglomerationor instability to produce planetesimals. A proposed scenario by which protoplanetarydisks fills with vortices will also be investigated. In this model a small, initialperturbation produces weak internal gravity waves. Those waves, in a rotating, shearingstratified flow, create vortices. The vortices are not steady, but oscillate, creating newgravity waves, and the disk fills with waves and vortices.The tools employed here are applicable to other problems as well, including thecirculation of Jupiter's atmosphere, modeling wake-vortices produced by wide bodyaircraft, and the role of particulates in climate pollution. The results of this work will bedisseminated to the public through public lectures and popular articles. A graduatestudent will be supported and trained in numerical modeling of fluid flows.

摘要本文的研究集中在围绕年轻恒星的原行星盘中的质量和角动量的输运。“湍流”或“涡流粘度”被用来解决各种各样的问题，包括角动量从圆盘向外的传输，使质量聚集到中心的原恒星上，尘埃的积累产生了星子，以及它们作为增强粘度的能力，使星子或行星能够在圆盘上径向迁移，远离它们形成的区域。然而，计算角动量、尘埃、星子和行星在圆盘内的输运，使用“涡流粘度”的输运率可能是不正确的。在这里，另一个过程的可持续性，磁流体动力学湍流（这是高度耗散的）及其传输角动量的能力，将作为圆盘电离的函数进行研究。此外，研究者之前的工作已经表明，涡流在传递角动量方面是有效的。他的3D模型进一步表明，颗粒可以被困在这些漩涡中并集中。使用两种新的代码，一种是混合粒子/气体代码，另一种是两相流代码，其中一相是气体，另一相是尘埃，在圆盘的中间平面上，在圆盘内形成的漩涡中，以及在湍流的涡间区域中，尘埃的积累将被检查。所有这些地点都被认为是尘埃聚集的区域，然后经历凝聚或不稳定，产生星子。原行星盘充满涡旋的设想也将被研究。在这个模型中，一个很小的初始扰动会产生微弱的内部重力波。这些波浪在旋转、剪切的分层流中产生涡流。漩涡不是稳定的，而是振荡的，产生新的重力波，圆盘上充满了波和漩涡。这里使用的工具也适用于其他问题，包括木星大气的环流，宽体飞机产生的尾流涡的建模，以及微粒在气候污染中的作用。这项工作的成果将通过公开讲座和通俗文章向公众传播。研究生将获得流体流动数值模拟方面的支持和培训。