Thin liquid films driven to spread on homogeneous surfaces by thermocapillarity can undergo frontal breakup and parallel rivulet formation with well-defined wavelength. Previous modal analyses have relieved the well-known divergence in stress that occurs at a moving contact line by matching the front region to a precursor film. Because the linearized disturbance operator is non-normal, a generalized, nonmodal analysis is required to probe film stability at all times. The effect of the contact line model on nonmodal stability has not been previously investigated. This work examines the influence of boundary slip on thermocapillary driven spreading using a transient stability analysis, which recovers the conventional modal results in the long-time limit. In combination with earlier work on thermocapillary driven spreading, this study verifies that the dynamics and stability of this system are rather insensitive to the choice of contact line model and that the leading eigenvalue is physically determinant, thereby assuring results that agree with the eigenspectrum. Modal results for the flat precursor film model are reproduced with appropriate choice of slip coefficient and contact line slope.
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http://dx.doi.org/10.1103/PhysRevE.70.046309 | DOI Listing |
Materials (Basel)
March 2024
Metallurgy Department, Montanuniversitaet of Leoben, Franz-Josef-Str. 18, A-8700 Leoben, Austria.
Due to the high computational costs of the Eulerian multiphase model, which solves the conservation equations for each considered phase, a two-phase mixture model is proposed to reduce these costs in the current study. Only one single equation for each the momentum and enthalpy equations has to be solved for the mixture phase. The Navier-Stokes and energy equations were solved using the 3D finite volume method.
View Article and Find Full Text PDFACS Omega
October 2023
Department of Chemical and Biological Engineering, American University of Sharjah, Sharjah 26666, United Arab Emirates.
The thermocapillary migration of a drop placed on a solid plate is examined. The Brochard model using the lubrication approximation provides both Marangoni and Poiseuille flow components. The present 2D model extends Brochard analysis and provides a solution for the dynamics of drop migration using extended boundary conditions at the advancing and receding contact lines to account for both Marangoni and Poiseuille flow components, derived approximate drop profiles, and conservation of mass.
View Article and Find Full Text PDFSoft Matter
July 2023
Optofluidics and Interface Science Laboratory, Department of Physics, National Institute of Technology Calicut, Kozhikode, India.
The generation and control of microscale flows are crucial for fundamental as well as applied aspects of microfluidics. Commonly employed strategies for creating microflows are based on electric field, magnetic field, surface tension, temperature, pressure, light, Among them, light as an external stimulus is gaining increased attention as it offers non-contact actuation, high spatial and temporal resolution, tunable wavelength and intensity, ease of miniaturization, and fast response. Optically tuning the surface tension is promising because a surface tension gradient of a few mN m along the liquid surface is sufficient to create a strong Marangoni flow.
View Article and Find Full Text PDFJ Colloid Interface Sci
July 2023
Department of Mechanical Engineering (Department of Mechanical and Aerospace Engineering after Apr. 2023), Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, 278-8510, Chiba, Japan. Electronic address:
Hypothesis: Multicellular convective structures that are induced in a fluid exposed to temperature difference are commonly observed in nature and in daily life. Different types of basic flow patterns are induced in a free liquid film by thermocapillary effect, whereas the formation of such multicellular structures has not been hitherto unravelled.
Experiments: A thin film of high-Prandtl-number liquid is prepared in a rectangular aperture of the order of 0.
Philos Trans A Math Phys Eng Sci
April 2023
Institute of Mathematics and Information Technologies, Altai State University, Barnaul, Russia.
The right choice of the appropriate mathematical model is crucial for evaluating the physical plausibility of modelling results. The issue of the correct application of the classical Boussinesq approximation for studying the heat and mass transfer in fluidic systems with a deformable boundary is a subject of scientific discussions despite the good agreement of numerous theoretical and numerical results obtained within the convection models based on the Oberbeck-Boussinesq equations with the data of physical experiments and observations. A comparative analysis of the results of numerical simulations in the framework of two-sided models based on the Navier-Stokes equations, and their Boussinesq approximation, is performed in the context of a convection problem in a locally heated two-phase system with a deformable interface.
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