Micromixing, local— measurement

In the preceding two sections, it was shown how to measure local micromixing intensity using intermaterial area distribution [H(log p)] and length scale distributions [H(logs)]. These tools are not directly applicable to 3D flows, because the resolution of the smallest length scales in 3D mixture structures is, to date, computationally prohibitive. In this section we present a predictive method for striation thickness distributions applicable to either 2D or 3D chaotic flows. 

Many heterogeneous reactions are accelerated by the enhanced micromixing properties of cavitating sound fields. Oscillating and transient bubbles create intense microstreaming in the vicinity of suspended solids. Macromixing is induced by acoustic streaming and the oscillation of bubbles in the sound field. In most cases, a locally different mass-transport coefficient is observed. A tenfold increase in mass-transfer coefficients compared with silent reactions was measured [18]. 

It is clear that the experimentally measured degree of mixing depends on the spatial resolution (compared to Lg) and on the time resolution (compared to Tg) of the probe used to estimate local concentrations in the mixture. The mixture appears as uniform if the scale of concentration fluctuations is smaller than the resolution of the probe. Generally, it is admitted that micromixing takes place in the range between molecular dimensions up to the scale where non-uniformities can be detected by usual means of ob-... 

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