Unstructured conservative level-set method for two-phase flows with insoluble surfactants
Insoluble surfactants modify the hydrodynamics and interfacial transport processes in two-phase flows. This work introduces a novel unstructured conservative level-set (UCLS) method for incompressible two-phase flows with insoluble surfactants and variable surface tension on three-dimensional colloc...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2026 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/457163 |
| Acceso en línea: | https://hdl.handle.net/2117/457163 https://dx.doi.org/10.1016/j.ijheatmasstransfer.2026.128547 |
| Access Level: | acceso abierto |
| Palabra clave: | Unstructured Conservative Level-Set (UCLS) Insoluble surfactants Marangoni stresses Collocated unstructured finite volume Unstructured flux-limiters Variable surface tension Two-phase flow Àrees temàtiques de la UPC::Enginyeria mecànica::Mecànica de fluids |
| Sumario: | Insoluble surfactants modify the hydrodynamics and interfacial transport processes in two-phase flows. This work introduces a novel unstructured conservative level-set (UCLS) method for incompressible two-phase flows with insoluble surfactants and variable surface tension on three-dimensional collocated unstructured meshes, while preserving surfactant mass. Surface tension is modeled as a function of interfacial surfactant concentration using the nonlinear Langmuir equation of state and its linearized approximation. A finite-volume framework discretizes transport equations on three-dimensional collocated unstructured grids. The fractional-step projection method resolves the pressure–velocity coupling. A smooth transition of physical properties is regularized by the UCLS function across the interface. The convective term in the transport equations is solved with accurate unstructured flux limiters, which minimize numerical diffusion and prevent numerical oscillations at the interface. The diffusive term of transport equations is discretized using a central difference scheme. Verification and validation tests include surfactant diffusion and convection at interfaces, gravity-driven rising bubbles, and droplet deformation under shear flows. In benchmark cases, the error in fluid-phase mass conservation is below 1e-12, and below approximately 1e-8 for mass conservation of surfactant. Furthermore, the effect of Marangoni number (Ma) on the drag coefficient in gravity-driven bubbles is investigated, showing that it increases as Ma increases. These results show that the proposed UCLS method can accurately and robustly capture complex surfactant-driven multiphase phenomena within a collocated unstructured finite-volume framework. |
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