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New image analysis methods for the study of mixing patterns in stirred tanks
Author(s) -
Guillard Fabrice,
Trägårdh Christian,
Fuchs Laszlo
Publication year - 2000
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.5450780201
Subject(s) - impeller , mixing (physics) , planar , planar laser induced fluorescence , oscillation (cell signaling) , mixing patterns , mechanics , transformation (genetics) , lagrangian coherent structures , binary number , scale (ratio) , topology (electrical circuits) , physics , vortex , control theory (sociology) , biological system , laser , optics , computer science , mathematics , chemistry , laser induced fluorescence , artificial intelligence , control (management) , quantum mechanics , computer graphics (images) , arithmetic , biology , biochemistry , combinatorics , gene
A method of treating data acquired with the planar laser‐induced fluorescence technique has been developed to visualize the topology of two‐dimensional concentration fields and to describe the dynamics of the coherent mixing structures identified. This method is based on a conditional binary transformation of the local concentration data, combined with a joint probability calculation. The methodology has been used to investigate the mixing in a stirred tank, at two injection port locations (in the bulk and in the impeller stream region). With bulk injection, a “folding phenomenon” of the coherent mixing structure was detected. Away from this port, large‐scale spatially periodic motion was identified, with a characteristic time of oscillation of the order of 2 to 3 s. With injection in the impeller stream region, no spatial instabilities of the coherent structure were detected. Local oscillations of the coherent mixing structure were found both on short and long time‐scales (i.e., ˜1 and ˜80 s).