Transport processes for a bubble entrapment during horizontal solidification

• Published in: International journal of thermal sciences Vol. 172; p. 107314
• Main Authors: Wei, P.S., Lin, P.Y.
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01.02.2022
• Subjects: Bubble entrapment; Horizontal solidification; Phase field modelling; Pore shape; Porous materials; Solute convection; Thermal convection; Solute convection; Horizontal solidification; Phase field modelling; Porous materials; Pore shape; Thermal convection; Bubble entrapment
• ISSN: 1290-0729; 1778-4166
• DOI: 10.1016/j.ijthermalsci.2021.107314

Transport processes coupling with shape development of a bubble captured by a solidification front advancing in a horizontal direction are numerically studied. Porosity in solid plays important roles on microstructure of materials and functional materials in biology, tissue, MEM, micro- or nano-engineering, foods, and geophysics, etc. In view of significant force torque, pore shape development during horizontal solidification is more significant than that during vertical solidification. In this work, transport equations of fluid flow, energy and concentration with sources governing interfacial balance of momentum, energy and concentration in the presence of a bubble entrapped by the solidification front were solved by the commercial COMSOL computer code. The results find the pore shape development affected by velocity, pressure and concentration fields for different gravity forces and flow boundary conditions. Prediction of contact angle agrees with that from Abel's equation during solidification, previously confirmed by experimental data. Controlling pore formation in solid via selecting different gravitational acceleration or ambient pressure and flow boundary conditions can therefore be achieved. ●Pore shape and solid concentration can be controlled by adjusting gravity force (or atmospheric pressure) or flow condition at boundaries.●Pore shape subject to different flow patterns is non-spherical for a significantly large gravity.●Existence of high concentration regions in triangular shapes covering solid and liquid near the triple-phase-line is susceptible to oscillations, especially for a high solidification rate.●Solid concentration through triangular region with high concentration are significantly affected by velocity profile at bottom boundary.●Effects of Marangoni forces, difference in densities between solid and liquid, and gravitational acceleration near a terrestrial condition on pore shape and solid concentration are negligibly small.