Mathematical Sciences: Shock Stability in Systems that Change Type

数学科学：改变类型的系统的冲击稳定性

• 批准号: 9103560
• 负责人: Barbara Keyfitz
• 金额: $ 0.5万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-07-01 至 1993-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9103560&HistoricalAwards=false
• 关键词: Mathematical; Sciences; Shock; Stability; Systems

In this project the principal investigator will continue her important work on the well-posedness of systems of partial differential equations that can change type. Such systems have solutions of shock-wave type that serve as mechanisms for the propoagation of waves, even in parts of the domain where the system is no longer hyperbolic. These types of problems occur in the transonic flow of gases and in the flow of multi-phase fluids through porous media. In particular, the principal investigator will study the stability of shock waves in systems of equations that undergo changes from hyperbolic to elliptic type using regularization and perturbation methods. The behavior of fluids (liquids and gases) under unusual conditions such as in the upper atmosphere or in the earth is governed by a complicated system of partial differential equations that can under go what is called a "change of type". Basically this means that the system has solutions of different kinds in different parts of the domain. As an illustration, think of the behavior of a seismic wave generated inside the earth by a earthquake. The wave passes through regions that are in liquid, solid or composite states. In this project the principal investigator will examine certain solutions of a system of model equations that exhibit change-of-type behavior that are known as "shock waves". The study of shock waves arises in such technologically important areas as transonic flow and flow through porous media.

在这个项目中，首席研究员将继续她在可改变类型的偏微分方程组的适定性方面的重要工作。 此类系统具有冲击波类型的解决方案，作为波传播的机制，即使在系统不再是双曲线的部分域中也是如此。 这些类型的问题发生在气体的跨音速流动和多相流体通过多孔介质的流动中。 特别是，首席研究员将使用正则化和微扰方法研究方程组中冲击波的稳定性，该方程组经历从双曲型到椭圆型的变化。 流体（液体和气体）在异常条件下（例如高层大气或地球中）的行为受到复杂的偏微分方程系统的控制，该系统可能会经历所谓的“类型变化”。 基本上，这意味着系统在域的不同部分具有不同类型的解决方案。 作为一个例子，请考虑地震在地球内部产生的地震波的行为。 波穿过液态、固态或复合态的区域。 在这个项目中，主要研究人员将检查模型方程组的某些解，这些解表现出称为“冲击波”的类型变化行为。 冲击波的研究出现在跨音速流和多孔介质流等技术重要领域。