Direct numerical simulations of intrusive density- and particle-driven gravity currents

Francisco, E. P.; Espath, L. F.R.; Laizet, S.; Silvestrini, J. H.; Calo, V. M.

Abstract

In the present study, mesopycnal flows are investigated using direct numerical simulations. In particular, intrusive density- and particle-driven gravity currents in the lock exchange setup are simulated with the high-order finite-difference framework Xcompact3d. To account for the settling velocity of particles, a customized Fick's law for the particle-solution species is used with an additional term incorporating a constant settling velocity proportional to the concentration of particles. A general energy budget equation is presented, for which the energy can migrate across the domain's boundaries. The relevant main features of intrusive gravity currents, such as front velocity, energy exchanges, sedimentation rate, deposit profile, and deposit map are discussed with the comparison between two- and three-dimensional simulations. In particular, the influence of the Grashof number, the interface thickness, the energy exchanges, the sedimentation process, and how the presence of more than one particle fraction may change the flow dynamics are investigated. The results are in good agreement with previous experiments and theoretical work, in particular for the prediction of the front velocity. For the particle-driven case, the suspended mass evolution along with the sedimentation rate suggests the occurrence of three different stages. In the first stage after the lock release, the particle mixture tends to suspend itself due to gravitational forces. Once most of the particle-mixture mass is suspended, the current intrudes while increasing its velocity, reaching its kinetic energy peak. In the last stage, the particles are deposited at a nearly constant sedimentation rate. As a result, the front velocity constantly decelerates.

Citation

Francisco, E. P., Espath, L. F., Laizet, S., Silvestrini, J. H., & Calo, V. M. (2022). Direct numerical simulations of intrusive density- and particle-driven gravity currents. Physics of Fluids, 34(4), Article 045116. https://doi.org/10.1063/5.0087595

• Journal Article Type: Article
• Acceptance Date: Mar 27, 2022
• Online Publication Date: Apr 13, 2022
• Publication Date: Apr 1, 2022
• Deposit Date: May 18, 2022
• Publicly Available Date: May 18, 2022
• Journal: Physics of Fluids
• Print ISSN: 1070-6631
• Electronic ISSN: 1089-7666
• Publisher: American Institute of Physics
• Peer Reviewed: Peer Reviewed
• Volume: 34
• Issue: 4
• Article Number: 045116
• DOI: https://doi.org/10.1063/5.0087595
• Public URL: https://nottingham-repository.worktribe.com/output/7955254
• Publisher URL: https://aip.scitation.org/doi/abs/10.1063/5.0087595
• Additional Information: This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared inE. P. Francisco, L. F. R. Espath, S. Laizet, J. H. Silvestrini, and V. M. Calo , "Direct numerical simulations of intrusive density- and particle-driven gravity currents", Physics of Fluids 34, 045116 (2022) https://doi.org/10.1063/5.0087595 and may be found at https://aip.scitation.org/doi/10.1063/5.0087595