Use of a finite-element method to interpret rheological effects in blade coating

Authors

  • Tim Sullivan,

    1. Department of AMES/Chemical Engineering and Center for Magnetic Recording Research, University of California, San Diego, La Jolla, CA 92093
    Current affiliation:
    1. AT&T Bell Laboratories, Murray Hill, NJ 07974
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  • Stanley Middleman,

    1. Department of AMES/Chemical Engineering and Center for Magnetic Recording Research, University of California, San Diego, La Jolla, CA 92093
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  • Roland Keunings

    1. Center for Advanced Materials, Lawrence Berkeley Laboratory, University of California, Berkeley, Berkeley, CA 94720
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Abstract

Data and finite-element simulations are presented for the blade coating of a series of Newtonian and non-Newtonian fluids. Numerical simulations for purely viscous fluids show good agreement with coating thickness data for Newtonian and relatively inelastic non-Newtonian liquids, including geometries for which lubrication theory is inaccurate. These simulations account for the shape of the free surface, with surface tension included, and incorporate realistic inflow and outflow boundary conditions. By comparing pressure distributions generated with the finite-element technique to those calculated using lubrication theory, it is shown that the simple lubrication theory analysis suffers from inadequate inflow and outflow boundary conditions. Comparison of these simulations with new experimental results for three well-characterized viscoelastic liquids, having nearly identical steady shear viscosities but different normal stress behavior, confirms speculations of earlier work with respect to the effect fluid rheology has on coating thickness.

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