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CFD simulation of flow and mixing in‐inline rotor‐stator mixers with complex fluids
Author(s) -
Vial Christophe,
Stiriba Youssef,
Trad Zaineb
Publication year - 2015
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.22121
Subject(s) - mechanics , computational fluid dynamics , laminar flow , rotor (electric) , dimensionless quantity , newtonian fluid , flow (mathematics) , stator , materials science , physics , mechanical engineering , engineering
The objective is to apply CFD methodology for the validation of the scale‐up of rotor‐stator units formed by flat blades and used as in‐line mixers under laminar flow conditions. The comparison between simulated and experimental data as a function of rotor geometry, rotation speed and flow rate has shown a good agreement in terms of power input and RTD curves both for Newtonian and power‐law fluids with a flow index between 0.2 and 1. The applicability of the virtual Couette analogy has been validated quantitatively and explained by the analysis of the local flow in the mixer. As a result, a shear coefficient independent of fluid rheology has been deduced from CFD data. This has been shown to depend only on the dimensionless gap when the length‐to‐diameter ratio is higher than 2.5. In this case, fast 2D simulations can provide a good approximation of the shear coefficient obtained from 3D calculations from which a master power curve can be deduced, but these are not able to predict flow transition, contrary to 3D computations. Finally, original correlations able to estimate the power and shear coefficients as a function of the mixer geometry have been established.