Dip coating of bidisperse particulate suspensions
Name
2110.00052v1.pdf
Description
Accepted version
Size
4.83 MB
Format
Adobe PDF
Checksum (MD5)
f65968c35ad79a9b3ef18cad506b9913
Author(s)
Jeong, Deok-Hoon
Lee, Michael Ka Ho
Thiévenaz, Virgile
Bazant, Martin Z
Sauret, Alban
Date Issued
April 10, 2022
Journal
Journal of Fluid Mechanics
Publisher
Cambridge University Press
Citation
Jeong D-H, Lee MKH, Thiévenaz V, Bazant MZ, Sauret A. Dip coating of bidisperse particulate suspensions. Journal of Fluid Mechanics. 2022;936:A36.
Version
Author's final manuscript
Abstract
Dip coating consists of withdrawing a substrate from a bath to coat it with a thin liquid layer. This process is well understood for homogeneous fluids, but heterogeneities, such as particles dispersed in liquid, lead to more complex situations. Indeed, particles introduce a new length scale, their size, in addition to the thickness of the coating film. Recent studies have shown that, at first order, the thickness of the coating film for monodisperse particles can be captured by an effective capillary number based on the viscosity of the suspension, providing that the film is thicker than the particle diameter. However, suspensions involved in most practical applications are polydisperse, characterized by a wide range of particle sizes, introducing additional length scales. In this study, we investigate the dip coating of suspensions having a bimodal size distribution of particles. We show that the effective viscosity approach is still valid in the regime where the coating film is thicker than the diameter of the largest particles, although bidisperse suspensions are less viscous than monodisperse suspensions of the same solid fraction. We also characterize the intermediate regime that consists of a heterogeneous coating layer and where the composition of the film is different from the composition of the bath. A model to predict the probability of entraining the particles in the liquid film depending on their sizes is proposed and captures our measurements. In this regime, corresponding to a specific range of withdrawal velocities, capillarity filters the large particles out of the film.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
Massachusetts Institute of Technology. Department of Mathematics
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Creative Commons Attribution-Noncommercial-ShareAlike
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DOI of Published Version
https://doi.org/10.1017/jfm.2022.79
