skip to main content

Title: Spreading dynamics of a partially wetting water film atop a MHz substrate vibration

A MHz vibration, or an acoustic wave, propagating in a solid substrate may support the convective spreading of a liquid film. Previous studies uncovered this ability for fully wetting silicon oil films under the excitation of a MHz Rayleigh surface acoustic wave (SAW), propagating in a lithium niobate substrate. Partially wetting de-ionized water films, however, appeared immune to this spreading mechanism. Here, we use both theory and experiment to reconsider this situation and show partially wetting water films may spread under the influence of a propagating MHz vibration. We demonstrate distinct capillary and convective (vibrational/acoustic) spreading regimes that are governed by a balance between convective and capillary mechanisms, manifested in the non-dimensional number θ{sup 3}/We, where θ is the three phase contact angle of the liquid with the solid substrate and We ≡ ρU{sup 2}H/γ; ρ, γ, H, and U are the liquid density, liquid/vapour surface tension, characteristic film thickness, and the characteristic velocity amplitude of the propagating vibration on the solid surface, respectively. Our main finding is that the vibration will support a continuous spreading motion of the liquid film out of a large reservoir if the convective mechanism prevails (θ{sup 3}/We < 1); otherwise (θ{sup 3}/We > 1),more » the dynamics of the film is governed by the capillary mechanism.« less
Authors:
;  [1]
  1. Chemical Engineering, Technion - Israel Institute of Technology, Haifa 32000 (Israel)
Publication Date:
OSTI Identifier:
22482447
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Fluids (1994); Journal Volume: 27; Journal Issue: 10; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; FILMS; LIQUIDS; MHZ RANGE; NIOBATES; OILS; SILICON; SOLIDS; SOUND WAVES; SUBSTRATES; SURFACE TENSION; WATER