Use of Direct Numerical Simulations and Lagrangian Methods in Turbulent Transport

摘要CTS-9503000托马斯汉拉蒂伊利诺伊大学 湍流传热分析的进展受到限制，因为需要比实验室研究中获得的更详细的有关脉动温度和速度场的统计信息。 拟议的研究通过使用超级计算机来计算随时间变化的三维温度场和速度场来满足这一需求。 它在三个方面是新颖的：它提供了广泛的普朗特数的结果。 我涉及（第一次）欧拉和拉格朗日的结果。 它探讨了使用拉格朗日方法来描述泥沙输运。 输运问题的通常方法是使用欧拉框架，在该框架中，写一个微分方程来描述空间中固定体积中的浓度变化。 在这项研究中要探讨的一个观点是，物理的理解出现在一个更自然的方式，通过使用拉格朗日框架工作，认为浓度场的传输物种（热标记或沉积物）的贡献，从一些源和汇。 对于所考虑的问题，基本的积木是从分散和无穷小的源在边界处。 头部传送系统是通过通道的湍流，在该通道中底壁被加热而顶壁被冷却。 将对Pr=0.05-40进行直接数值模拟。 拉格朗日方法将被用来扩展这些普朗特数高达2000年。 本文将研究水平矩形槽道中泥沙的紊流输运。

ABSTRACT CTS-9503000 Thomas Hanratty Univ. of Illinois Advances in the analysis of turbulent heat transfer have been limited because of the need for more detailed information about the statistics of the fluctuating temperature and velocity fields than is obtained in laboratory studies. The proposed research responds to this need by using supercomputers to calculate the time-dependent, three-dimensional temperature and velocity fields. It is novel in three ways: It supplies results over a wide range of Prandtl numbers. I relates (for the first time) Eulerian and Lagrangian results. It explores the use of Lagrangian methods to describe sediment transport. The usual approach to transport problems is to use an Eulerian framework in which a differential equation is written to describe the concentration changes in a fixed volume in space. A viewpoint to be explored in this research is that physical understanding emerges in a more natural way by using a Lagrangian frame work, which considers concentration fields of a transported species (thermal markers or sediment) as resulting from the contributions of a number of sources and sinks. For the problems considered, the fundamental building block is dispersion from and infinitesimal source at the boundary. The head transfer system is turbulent flow through a channel in which the bottom wall is heated and the top wall is cooled. Direct numerical sumulations will be carried out for Pr=0.05-40. Lagrangian methods will be used to extend these to Prandtl numbers as high as 2000. Turbulent transport of sediment in a horizontal rectangular channel will be considered.