Thermal boundary layer modelling for heat flux prediction of bubbles at saturation: A priori analysis based on fully-resolved simulations - Institut des Sciences Appliquées et de la Simulation pour les énergies bas carbone Access content directly
Journal Articles International Journal of Heat and Mass Transfer Year : 2024

Thermal boundary layer modelling for heat flux prediction of bubbles at saturation: A priori analysis based on fully-resolved simulations

Abstract

This study presents and investigates uni-directional thermal sub-layer enhancement techniques within the context of an interface tracking method for simulating bubbly flows at saturation. Current discretisation methods on structured and fixed Cartesian grids tend to spread the bubbles' interface region, creating a trade-off between the freely moving nature of the bubble to the detriment of accurately capturing the discontinuous aspect of the interface and variations of properties and fluxes crossing it. Although robust techniques have been described in the literature to ensure energy conservation, less research has been undertaken to develop a methodology to retrieve the non-linear behaviour of quantities in the interface vicinity at a reasonable computational cost. In this study, the discretised bubble surface is used as a basis for incorporating several quasi-static radial sub-problems that are bounded by an interfacial constant saturation temperature and a CFD temperature field value. A first approach based on an analytical solution fitted at each time step has been developed to incorporate near-interface physics, including the tangential effect, incoming fluid velocity, and local curvature. A semi-analytical approach needs some strong assumptions to be valid which limits its applicability range. Therefore, a second approach based on a uni-directional sub-resolution fed carefully by tangential source terms demonstrates promising results as it aligns with the principal variations of the solution. Both methodologies have been applied a priori on a steady rising bubble configuration at low and moderate Reynolds {3.6; 62.5} and Prandtl {1; 2.5; 5} numbers with a constant interfacial temperature after an extensive analysis of the advection-diffusion terms hierarchy. The newly predicted interfacial temperature gradient and temperature profile could be re-employed for Eulerian fluxes correction.
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Dates and versions

cea-04419812 , version 1 (26-01-2024)

Identifiers

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Mathis Grosso, Guillaume Bois, Adrien Toutant. Thermal boundary layer modelling for heat flux prediction of bubbles at saturation: A priori analysis based on fully-resolved simulations. International Journal of Heat and Mass Transfer, 2024, 222, pp.124980. ⟨10.1016/j.ijheatmasstransfer.2023.124980⟩. ⟨cea-04419812⟩
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