Axial Dispersion Model for Laminar Flow in Round Tubes

Example 12.5.a-l Axial Dispersion Model for Laminar Flow in Round Tubes 

This is one situation where the exact convective-diffusion equation can be solved and compared with the one-dimensional dispersion equation. The complete equation is 

Taylor [38] has discussed this in detail, and a summary of the results is ven here. Taylor and Aris [39] showed that the main variable of interest, the mean concentration. 

For this case, these results provide a theoretical basis for an effective transport model. The dispersion coefficient, D is the sum of the ordinary diffusion contribution, and the second term that actually represents the effect of the velocity 

The practical importance of this Taylor diffusion analysis lies in the justification of the effective transport models to take into account complicated velocity and concentration profiles in a simple manner, as well as providing a theoretical framework for the dispersion coefficient, D . Similar results have been worked out for turbulent flow, packed columns, and other situations. For correlations of the axial dispersion coefficients, see Himmelblau and Bischoff [4] and Wen and Fan [2]. 

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