Study of Chaotic Rapid Variation of Heat and Fluid Flow in Porous Media

到目前为止，理论上一直采用局部体积平均技术来建立描述多孔介质中输运现象的控制方程。然而，将这种局部体积平均技术应用于快速瞬变换热和流体流动现象时，可能无法考虑多孔介质微观固体基质的有限热容量对非均匀温度分布的时间响应的影响，因为波动的瞬时传导仅限于固相表面而不是固体结构的全部体积，其中只涉及与瞬变现象的时间常数相关的部分热容。复杂微观流动通道应用的最新趋势将要求阐明在混沌和湍流区域中描述基本瞬变热和流体流动的详细理论框架，同时考虑t…。本研究采用狭窄Hele-Shaw缝隙中的管束作为多孔介质的模型，对微观固体结构中的微观速度和温度波动进行了实验和数值分析，(1)阐明了微观固体结构中的温度场，特别是高速温度变化的有效热容概念中的穿透尺度，(2)从微观温度场随时间变化的局部体积平均的观点来检验一个新的控制方程。在此基础上，讨论了一种新的描述流体流动和传热特性的模型。虽然到目前为止，微观多孔结构的总热容对瞬时换热的时间响应有很大的贡献，但本研究提出了一种新的方法来建立宏观能量方程，该方程适用于具有固液两相温差的非均质体系。较少

The local volume-averaging technique has been applied theoretically so far to formulate the governing equations to describe transport phenomena in porous media. However, the application of this local volume-averaging technique to highly quick transient heat-transfer and fluid-flow phenomena may fail to consider the effect of the finite heat capacity of microscopic solid matrices of porous media with the respect of the time response in inhomogeneous temperature distributions, since the transient conduction of fluctuations is limited to the surface of the solid phase but not to the entire volume of the solid structures, where only the part of the heat capacity will be involved with relevance to the time constant of the transient phenomena. Recent trends of the applications with complicated microscopic flow passages will require the elucidation of the detailed theoretical framework of the basic transient heat and fluid flow description in chaotic and turbulent regimes, taking account of t … More he two types of vortices, i.e., pseudo vortex to reflect the thermal dispersion with representative scale of the microscopic porous structures and interstitial vortex to reflect the Forchheimer resistance with the representative scale gap width.The present study, adopting a bank of tubes in a narrow Hele-Shaw gap as a model of a porous medium, made an experimental and numerical analysis on microscopic velocity and temperature fluctuations, (1) clarifying temperature fields in microscopic solid structures with particular attention on the penetrating scale in the concept of the effective heat capacity for high-speed temperature variations, and (2) examining a new governing equation from the viewpoint of time dependent local volume-averaging of microscopic temperature fields. Then a new modeling to describe the transient heat transfer and fluid flow characteristics with the concent of partial was discussed.Although it has been widely accepted so far that the entire heat capacity of the microscopic porous structures contributes to the time response to the transient heat transfer, the present study suggests the need of a new approach to formulate the macroscopic energy equation, which is to be applied to the system with inhomogeneity with temperature difference between solid and fluid phases. Less