A hybrid atomistic-continuum framework for multiscale simulations of boiling

Gennari, Gabriele; Smith, Edward R.; Pringle, Gavin J.; Magnini, Mirco

Abstract

Boiling is a multiscale physics process where the nucleation of vapour bubbles occurs due to molecular-scale interactions between the fluid and a heated wall, but it also depends on the larger-scale hydrodynamics and thermal boundary layers determined by the outer system boundary conditions. Modelling boiling from the nanometre up to the millimetre scales at which bubble departure occurs is not possible via state-of-the-art simulation methods: Molecular Dynamics (MD) simulations can capture nucleation from first principles but are limited to nanometre scales due to their computational cost, whereas computational fluid dynamics (CFD) simulations based on the continuum Navier-Stokes equations cannot capture nucleation. Here, we present a novel multiscale simulation method which merges MD and CFD descriptions into a single modelling framework, where MD resolves the near-wall region where molecular interactions are important, and a CFD solver resolves the bulk flow. We model the progressive heating of a Lennard-Jones fluid via contact with a solid wall until a vapour bubble nucleates in the MD region of the domain and grows by entering in the CFD domain. Our results show that an incompressible CFD flow model based on the Volume Of Fluid method with interphase mass transfer calculated via the Hertz-Knudsen-Schrage equation is sufficient to obtain seamless coupling of phase fraction, velocity and temperature fields, with the hybrid MD-CFD framework yielding bubble dynamics closely matching those of MD alone.

Citation

Gennari, G., Smith, E. R., Pringle, G. J., & Magnini, M. (2024, June). A hybrid atomistic-continuum framework for multiscale simulations of boiling. Presented at 9th European Thermal Sciences Conference (Eurotherm 2024), Lake Bled, Slovenia

• Presentation Conference Type: Conference Paper (published)
• Conference Name: 9th European Thermal Sciences Conference (Eurotherm 2024)
• Start Date: Jun 10, 2024
• End Date: Jun 13, 2024
• Acceptance Date: May 8, 2024
• Online Publication Date: Jun 3, 2024
• Publication Date: Jun 10, 2024
• Deposit Date: Nov 18, 2024
• Publicly Available Date: Nov 19, 2024
• Journal: Journal of Physics: Conference Series
• Print ISSN: 1742-6588
• Electronic ISSN: 1742-6596
• Publisher: IOP Publishing
• Peer Reviewed: Peer Reviewed
• Volume: 2766
• Issue: 1
• Article Number: 012151
• DOI: https://doi.org/10.1088/1742-6596/2766/1/012151
• Public URL: https://nottingham-repository.worktribe.com/output/36000695
• Publisher URL: https://iopscience.iop.org/article/10.1088/1742-6596/2766/1/012151