Direct numerical simulations of a thin liquid film coating an axially oscillating cylindrical surface

2014 ◽  
Vol 46 (4) ◽  
pp. 041402 ◽  
Author(s):  
Matthias Binz ◽  
Wilko Rohlfs ◽  
Reinhold Kneer
Keyword(s):  
Liquid Film ◽  
Numerical Simulations ◽  
Cylindrical Surface ◽  
Thin Liquid Film ◽  
Film Coating ◽  
Direct Numerical Simulations

scholarly journals Flow of a thin liquid film coating a horizontal stationary cylinder

2013 ◽  
Vol 88 (6) ◽  
Author(s):  
M. Cachile ◽  
M. A. Aguirre ◽  
M. Lenschen ◽  
A. Calvo
Keyword(s):  
Liquid Film ◽  
Thin Liquid Film ◽  
Film Coating

Hydromagnetic Stability Analysis of a Film Coating Flow Down a Rotating Vertical Cylinder

2011 ◽  
Vol 27 (1) ◽  
pp. 27-36 ◽  
Author(s):  
P.-J. Cheng ◽  
K.-C. Liu ◽  
D. T. W. Lin
Keyword(s):  
Liquid Film ◽  
Thin Liquid Film ◽  
Vertical Cylinder ◽  
Film Coating ◽  
Rossby Number ◽  
Free Film ◽  
Coating Flow ◽  
The Stability ◽  
Film Flows ◽  
The Magnetic Field

ABSTRACTThe influence of both the Rossby number and the Hartmann number on the hydromagnetic stability of a thin liquid film flowing down along the surface of a vertical cylinder is investigated. The long-wave perturbation method is employed to solve for generalized nonlinear kinematic equations with a free film interface. The normal mode approach is used to compute the stability solution for the film flow. The modeling results indicate that the stability of the liquid film is enhanced by increasing the strength of the magnetic field or reducing the speed at which the cylinder rotates. By contrast, the flow becomes relatively more unstable as the cylinder radius is increased at larger values of the Rossby number. Notably, this finding is the opposite of that observed for film flows along a stationary vertical cylinder.

Nonlinear Evolution of the Travelling Waves in Roll Coating Flows of Thin Viscoelastic Polymer Falling Films

2013 ◽  
Vol 479-480 ◽  
pp. 45-49 ◽  
Author(s):  
Po Jen Cheng ◽  
Kuo Chi Liu ◽  
Cheng Chi Wang
Keyword(s):  
Liquid Film ◽  
Film Growth ◽  
Travelling Waves ◽  
Flexible Substrate ◽  
Thin Liquid Film ◽  
Film Coating ◽  
Viscoelastic Parameter ◽  
Roll Coating ◽  
Viscoelastic Polymer ◽  
Roller Radius

Roll coating is widely used to apply a thin liquid film to a continuous, flexible substrate. It is known that macroscopic instabilities of the film system can result in a non-homogenous film growth to fluid flow. The influence of the Rossby number, the viscoelastic parameter, and the roller radius on the nonlinear hydrodynamic stability of a thin viscoelastic polymer fluid film coating flow down a rotating vertical roller is investigated. In contrast to most previous studies, the solution scheme employed in this study is based on a numerical approximation approach rather than an analytical method. The size of the explosive supercritical instability region increases significantly as the roller rotates. It is shown that the stability of the liquid film is enhanced by reducing the viscoelastic effect or decreasing the speed of the rotating roller. At higher values of the Reynolds number, the tendency of the rotation effect to prompt thin-film instability increases with an increasing roller radius.

scholarly journals Droplet impact on a thin liquid film: anatomy of the splash

2016 ◽  
Vol 802 ◽  
pp. 775-805 ◽  
Author(s):  
Christophe Josserand ◽  
Pascal Ray ◽  
Stéphane Zaleski
Keyword(s):  
Reynolds Number ◽  
Liquid Film ◽  
Numerical Simulations ◽  
Thin Liquid Film ◽  
Droplet Impact ◽  
The Other ◽  
Dimensionless Number ◽  
Scaling Analysis ◽  
The Impact ◽  
Short Times

We investigate the dynamics of drop impact on a thin liquid film at short times in order to identify the mechanisms of splash formation. Using numerical simulations and scaling analysis, we show that it depends both on the inertial dynamics of the liquid and the cushioning of the gas. Two asymptotic regimes are identified, characterized by a new dimensionless number $J$: when the gas cushioning is weak, the jet is formed after a sequence of bubbles are entrapped and the jet speed is mostly selected by the Reynolds number of the impact. On the other hand, when the air cushioning is important, the lubrication of the gas beneath the drop and the liquid film controls the dynamics, leading to a single bubble entrapment and a weaker jet velocity.

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