Light Scattering Studies in Fluids

建议研究开式和闭式湍流中的小尺度速度差。特别令人感兴趣的是从混沌状态(几个自由度)到完全湍流状态的交叉，在这种状态下可以应用湍流的“级联”思想。湍流将通过激光多普勒测速等传统技术探测，也可以通过零差光散射进行探测，零差光散射允许在不作“冻结湍流”假设的情况下测量速度差。还需要研究的还有：多孔介质中包含的流体和液晶的相分离动力学；以及均匀剪切下流体混合物中的成核。贯穿所有这些工作的共同主线是远离平衡的系统的主线。%这项研究涉及的是“自相似”现象，即在所有放大比例下，它们看起来都是一样的。湍流流体表现出这种自相似性，这将通过光散射来研究。另一种自相似现象是约束在多孔介质中的流体的运动(例如，沙子中的油)。我们的目标是理解这种自相似性的起源。

It is proposed to study small-scale velocity differences in open and closed turbulent flows. Of special interest is the cross-over from the chaotic state (few degrees of freedom) to the fully turbulent state, where "cascade" ideas of turbulence may be applied. The turbulence will be probed by conventional techniques, such as laser Doppler velocimetry, and also by homodyne light scattering, which permits the measurement of velocity differences without making the "frozen-turbulence" assumption. Also to be studied are: the dynamics of phase-separation of fluids and liquid crystals contained in porous media; and nucleation in fluid mixtures under uniform shear. The common thread running through all of this work is that of systems driven far from equilibrium. %%% The research deals with "self-similar" phenomena which have the property that they look the same when viewed on all scales of magnification. Turbulent fluids exhibit this self-similarity, which will be studied by light scattering. Another self-similar occurrence is the motion of fluids constrained within porous media (e.g., oil in sand). The goal is to understand the origin of this self-similarity.