Flows, Polymers and Random Media

流动、聚合物和随机介质

• 批准号: 1007176
• 负责人: Michael Cranston
• 金额: $ 35.93万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-15 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1007176&HistoricalAwards=false
• 关键词: Flows; Polymers; Random; Media

The PI proposes to carry on research on problems in stochastic flows, the parabolic Anderson model, polymer phase transitions and random Schrodinger operators. In the area of stochastic flows, the PI will continue efforts on the distribution of passive tracers under the motion of stochastic flows. Here, the goal will be to investigate the joint asymptotic distribution of two disjoint bodies of passive tracers moving under the flow. This will also be investigated for the case of turbulence where the tracers are carried by Kolmogorov velocity fields. Other research will be carried out involving the behavior of the singular flows called Kraichnan flows. In the area roughly labeled the parabolic Anderson model, the PI will investigate the so-called dynamo problem. This involves a model for the generation of magnetic fields in turbulent media such as on the surface of a star. The dynamo conjecture is that the magnetic field of a star will exhibit exponential growth. The PI will attempt to establish this exponential growth and examine the asymptotics of the exponential constant as the inverse Reynolds number goes to zero.The general spirit of this proposal is to pursue a mathematical investigation ofphysical phenomena in the presence of random and chaotic media. Examples of thisin the investigations in stochastic flows are provided by the distribution of plankton particles when carried by ocean currents or the spread of oil as in the recent disaster in the Gulf of Mexico. The goal of this study is to give information on the distribution and shape of a body of particles being carried by a random current. Another example of phenomena in chaotic media is the creation of magnetic fields in young stars. The field strength is conjectured to exhibit rapid growth and the mathematical model should also have the high focusing of the magnetic field strength in small regions which are sun spots. This will lead to more understanding of the development of these spots which have an effect on events on earth. Another project relates to behavior of polymer chains. One aspect of this work will be to make a detailed study of the phase transitions of polymers and the effect the relation of length to temperature has on the nature of the transition. Another aspect of the polymer study is to gauge the effect that a random environment has on the shape of a polymer. So far, very noisy environments have been shown to force the polymer into a particular shape, that is intense randomness reduces the degrees of freedom of the polymer in the model. We aim to gain more insight into the nature of this particular shape.

PI建议进行随机流、抛物安德森模型、聚合物相变和随机薛定谔算子问题的研究。在随机流领域，PI将继续致力于随机流运动下被动示踪剂的分布。在这里，我们的目标将是调查联合渐近分布的两个不相交的机构的被动示踪剂下移动的流动。这也将被调查的情况下，示踪剂进行Kolmogorov速度场的湍流。其他的研究将涉及称为Kraichnan流的奇异流的行为。在大致标记为抛物线安德森模型的区域，PI将研究所谓的发电机问题。这涉及到一个在湍流介质中产生磁场的模型，例如在星星表面。发电机猜想是星星的磁场将呈指数增长。PI将尝试建立这种指数增长，并检查指数常数的渐近性，因为逆雷诺数趋于零。这个建议的一般精神是追求随机和混沌介质中存在的物理现象的数学研究。这在随机流的调查中的例子是由浮游生物颗粒的分布时，由洋流或石油的传播，如在最近的灾难在墨西哥湾。这项研究的目的是提供信息的分布和形状的一个身体的粒子被携带的随机电流。另一个混沌介质现象的例子是年轻恒星中磁场的产生。磁场强度必须呈现快速增长，并且数学模型还应该在太阳黑子的小区域中具有磁场强度的高聚焦。这将导致更多的了解这些景点的发展，对地球上的事件产生影响。另一个项目涉及聚合物链的行为。这项工作的一个方面是详细研究聚合物的相变和长度与温度的关系对相变性质的影响。聚合物研究的另一个方面是衡量随机环境对聚合物形状的影响。到目前为止，非常嘈杂的环境已被证明可以迫使聚合物形成特定的形状，即强烈的随机性降低了模型中聚合物的自由度。我们的目标是更深入地了解这种特殊形状的本质。