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Single and multiphase CFD approaches for modelling partially baffled stirred vessels: comparison of experimental data with numerical predictions

Torré, Jean-Philippe and Fletcher, David F. and Lasuye, Thierry and Xuereb, Catherine Single and multiphase CFD approaches for modelling partially baffled stirred vessels: comparison of experimental data with numerical predictions. (2007) Chemical Engineering Science, Vol. 62 (n°22 ). pp. 6246-6262. ISSN 0009-2509

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Official URL: http://dx.doi.org/10.1016/j.ces.2007.06.044

Abstract

Whilst the use of CFD to study mixing vessels is now common-place, there are still many specialised applications that are yet to be addressed. Here we present CFD and PIV results for a hydrodynamic study of a partially baffled vessel with a free surface. The standard k.ε and SSG Reynolds Stress turbulence models are used and the numerical predictions of the mean flow field are compared with experimental data for single phase modelling. At low rotation rates a flat free surface is observed and the flow is simulated using a single phase model, whilst at high rotation rates an Eulerian–Eulerian multiphase model is used to capture the free surface location, even under conditions when gas is drawn down to the impeller. It is shown that there are significant transient effects that mean many of the “rules of thumb” that have been developed for fully baffled vessels must be revisited. In particular such flows have central vortices that are unsteady and complex, transient flow-induced vortical structures generated by the impeller–baffle interactions and require a significant number of simulated agitator rotations before meaningful statistical analysis can be performed. Surprisingly, better agreement between CFD and experimental data was obtained using the k.ε than the SSG Reynolds stress model. The multiphase inhomogeneous approach used here with simplified physics assumptions gives good agreement for power consumption, and with PIV measurements with flat and deformed free surfaces, making this affordable method practical to avoid the erroneous modelling assumption of a flat free surface often made in such cases.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com/science/article/pii/S0009250907004903
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:Other partners > University of Sydney (AUSTRALIA)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Other partners > LVM (FRANCE)
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
French research institutions > Centre National de la Recherche Scientifique - CNRS
Laboratory name:
Laboratoire de Génie Chimique - LGC (Toulouse, France) - Réaction, mélange & séparation (RMS)
Statistics:download
Deposited By: Catherine XUEREB

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