Macromixing residence-time, mean

Macromixing The phenomenon whereby residence times of clumps are distributed about a mean value. Mixing on a scale greater than the minimum eddy size or minimum striation thickness, by laminar or turbulent motion. 

In the statistical theory of fluid mixing presented in Chapter 3, well macromixed corresponds to the condition that the scalar means () are independent of position, and well micromixed corresponds to the condition that the scalar variances are null. An equivalent definition can be developed from the residence time distribution discussed below. 

Figure 3.14. Microbial growth in dependence on micromixing and macromixing dimensionless cell mass concentration x as a function of internal recycle ratio r in a recycle reactor at different values of total Bo number (Bo ot as a measure of macromixing) and varying mean residence time t. (Adapted from Dohan and Weinstein, 1973. With permission from Ind. Eng. Chem. Fundam., 12, 64. Copyright American Chemical Society).

---