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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Article
Author(s)
Badra Ali Talha1, Hocine Alla1,, Somia Freifer1 and Thibault Roques-Carmes2, 3
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DOI:10.17265/2161-6221/2013.12.008
Affiliation(s)
1. Laboratoire de Physique des Matériaux Et des Fluides, Université des Sciences et de la Technologie d'Oran, BP 1505 El M'Naouar Bir el Djir 31000, Oran, Algeria 2. Université de Lorraine, Laboratoire Réactions et Génie des Procédés, UMR 7274 CNRS, Nancy, F-54000, France 3. CNRS, Laboratoire Réactions et Génie des Procédés, UMR 7274 CNRS, Nancy, F-54000, France
ABSTRACT
The dynamics of drop spreading on horizontal smooth surfaces of different wettabilities is revisited using computational
fluid dynamics (CFD). For this purpose, a recently developed CFD model, based on the volume of fluid technique (VOF), with piecewise linear interface calculations method (PLIC) for interface reconstruction, is generalized and applied to simulate the time evolution of spreading drops on solid surfaces (drop base radius and dynamic contact angle). The CFD simulations are quantitatively compared with previously published experimental results from other research groups. The influence of different factors, such as oils nature (silicone, mineral, peanut and coconut), viscosity (0.02-1 Pa·s), drop volume (0.3-38 μL) and type of surfaces (hydrophilic glass, stainless steel and hydrophobic glass) on the temporal evolution of the drop base radius and contact angle is investigated. For hydrophilic surfaces, the predictions of the CFD model agree remarkably well with the measurements. For hydrophobic surfaces, a small deviation between calculated and experimental results occurs because the model does not consider the partial slippage which can take place on hydrophobic materials. Despite neglecting this aspect, the simulations are found to capture the key features of drop spreading on hydrophobic surface. The fact that we obtain a good agreement between the proposed theory and the experimental results for a large range of oils and surfaces over five decades of time is a strong argument in favor of the model. The accuracy of the model demonstrates also that the influence of the surface wettabity (partial wetting and complete wetting) can be successfully simulated. The numerical results reproduce perfectly the spreading regimes which occur during the time course of the drop. The succession of two different regimes takes place in the following order: a hydrodynamic regime followed by a gravity regime.
KEYWORDS
Spreading dynamics, CFD simulation, oils, hydrophobic surfaces.
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