Paper 4: Instabilities in downslope propagating gravity currents

Skevington, Edward W G; Lloyd, Charlie J; Atoufi, A; Doak, A

Abstract

In this paper, the stability of a gravity current propagating down an inclined channel is explored. The gravity current is generated through a partial lock release. A local analysis of the flow about the lock is conducted using classical methodologies in two-layer shallow water theory, which is here developed to allow for drag and an angled channel. A global analysis of the flow is done by exploring the long-time forced steady state, using non-linear simulations solving the full three-dimensional Navier-Stokes equations. A steady state is forced through the inclusion of a so-called mask function. For sufficiently large slope angles, wave-like instabilities are observed on the density interface (pycnocline) of the generated gravity current. Spectral Proper-Orthogonal Decomposition of the time-series data provides evidence that instability arises via the interaction of two asymmetric vorticity waves, occurring on either side of a critical layer, akin to a spatially evolving Kelvin-Helmholtz instability. The work in this paper is exploratory in nature and motivates further investigation.

Citation

Skevington, E. W. G., Lloyd, C. J., Atoufi, A., & Doak, A. (2023, July). Paper 4: Instabilities in downslope propagating gravity currents. Presented at NFFDy Summer Programme on ‘Data in Fluids’, Cambridge

• Presentation Conference Type: Conference Paper (published)
• Conference Name: NFFDy Summer Programme on ‘Data in Fluids’
• Start Date: Jul 10, 2023
• End Date: Aug 18, 2023
• Acceptance Date: Mar 15, 2024
• Online Publication Date: Mar 26, 2024
• Publication Date: Mar 26, 2024
• Deposit Date: Mar 26, 2024
• Publicly Available Date: Apr 4, 2024
• Book Title: Proceedings of the NFFDy Summer Programme on ‘Data in Fluids’
• DOI: https://doi.org/10.17863/CAM.107271
• Public URL: https://hull-repository.worktribe.com/output/4612644
• Publisher URL: https://www.repository.cam.ac.uk/handle/1810/366290