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Hysteresis and non-uniqueness in the speed of the onset of instability in curtain coating

Published online by Cambridge University Press:  15 November 2006

J. O. MARSTON
Affiliation:
School of Mathematics, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK Department of Chemical Engineering, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
S. P. DECENT
Affiliation:
School of Mathematics, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
M. J. H. SIMMONS
Affiliation:
Department of Chemical Engineering, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK

Abstract

The maximum speed of stable coating is determined experimentally by the onset of air entrainment in curtain coating onto a pre-wetted surface over a broad range of dimensionless parameters (Reynolds number: $0.14\,{<}\,\hbox{\it Re}\,{<}\,33.02$; capillary number: $0.19\,{<}\,\hbox{\it Ca}\,{<}\,25.07$). We show not only that the substrate speed at the onset of instability is flow-rate dependent for a pre-wetted surface, but that the speed at which instability occurs is not always unique for a given flow rate.

Type
Papers
Copyright
© 2006 Cambridge University Press

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