Mass Transfer and Transport Processes in Two-Phase Flow

该项目延续了早期NSF支持的两相流输运过程的成功研究。总的目标是了解分子种类的湍流输运是如何与拉格朗日统计相关的，了解粒子、液滴和气泡的湍流输运，这些粒子、液滴和气泡的密度与它们悬浮的流体不同，了解固体/液体或气体/液体边界处的质量湍流输运如何与界面附近的流体力学因素相关，并了解空气在液体表面上流动引起的非线性波。提出了五个项目：(1)将拉格朗日和欧拉对湍流输运的描述联系起来的计算机研究，并提供关于分子扩散率在减少湍流输运中的作用的信息；(2)液滴、粒子和气泡湍流输运的光学研究；(3)波浪对分层流动中气体吸收的影响；(4)气液分层流动的有限幅值波；(5)固液边界处的紊流传质。这项工作的重要方面是将进行实验室和超级计算机实验的结合，并将使用新开发的光学技术来研究粒子，液滴和气泡的拉格朗日湍流特性，最后，从这项研究中得出的最直接的结果之一将是应用于开发改进的管道中气/液流动设计方程。研究气体吸收的系统在许多工艺问题中具有实际意义。然而，地球物理学家也对此感兴趣，因为在环境水体表面的转移是许多物质的地球物理和自然生化循环的一个重要阶段。这解释了化学家、地球物理学家、土木工程师、机械工程师和环境学家对它的广泛兴趣。

The program outlined continues successful earlier NSF supported research in transport process in two phase flow. The general objectives are to understand how turbulent transport of molecular species is related to Lagrangian statistics, to understand the turbulent transport of particles, droplets and bubbles that have a density different from the fluid in which they are suspended, to understand how the turbulent transport of mass at a solid/liquid or a gas/liquid boundary is related to fluid mechanical factors close to the interface, and to understand non-linear waves caused by air flow over a liquid surface. Five projects are proposed: (1) Computer studies that relate the Lagrangian and Eulerian descriptions of turbulent transport, and that provide information on the role of molecular diffusivity in diminishing turbulent transport; (2) Optical studies on the turbulent transport of drops, particles and bubbles; (3) Influence of waves on gas absorption in stratified flows; (4) Finite amplitude waves in gas-liquid stratified flows; (5) Turbulent mass transfer at a solid- liquid boundary. Important aspects of this work are that combined laboratory and supercomputer experiments will be conducted and that newly developed optical techniques will be used to study Lagrangian turbulence characteristics of particles, drops and bubbles and finally, one of the most immediate consequences to be derived from this study will be the application leading to development of improved design equations for gas/liquid flow in pipelines. The system chosen to study gas absorption is of practical importance in many process problems. However, it is also of interest to geophysicists, since the transfer across the surface of environmental waters is an important phase of the geophysical and natural biochemical cycles of numerous substances. This explains the widespread interest in it by chemists, geophysicists, civil engineers, mechanical engineers, and environmentalists.