Theoretical prediction of micro-mixing

Brodkey [56] stated that only with the advent of the modem turbulence theory a deep understanding of micro-mixing processes and turbulent scalar transfer processes on a microscopic level was possible and that this theory enabled the definition of measurable mixing criteria. Knowledge of the turbulence parameter made it possible to estimate the degree of mixing. The parameters could be estimated from the geometry of the flow system and from simple empirical expressions. The 

High speed microphotography showed [331] that fluid elements injected from a point source tended to exhibit slice-like and strip-like configurations rather than lamellar structure during the turbulent mixing of fluids with Sc 1. Based on this phenomenon a new micromixing model was developed. It starts from the propo- 

Above Diazo-coupling of 1-naphthol A with diazotised sulphanilic acid B to bis-azo-dye S via intermedia products o- and p-mono-azo-dyes. 

Belour Diazo-coupling of 2-naphthol AA with diazotized sulphanylic acid B to mono-azo-dye Q 

A simplified mathematical description of this three-zone model proved [332], however, that the quantity of material converted in the dispersion zone could be ignored, if the original concentration ratio of A and B was less than 0.1 and the action of micro- and macro-mixing is described by the Damkohler number Da = fczCBo/s and n = 27twD/ qs) (where w is the flow rate D is the dispersion coefficient q is the liquid throughput and s [s ] is the shrinkage rate of the volume element). The model was evaluated with competitive reactions in series and parallel reactions, and was found to be adequately applicable. 

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