The dynamics of a subglacial salt wedge

• Published in: Journal of fluid mechanics 2020-07, Vol.895, Article A20
• Main Authors: Wilson, Earle A., Wells, Andrew J., Hewitt, Ian J., Cenedese, Claudia
• Format: Article
• Language: English
• Subjects: Channels; Chemical analysis; Computational fluid dynamics; Drag coefficient; Drag coefficients; Dynamics; Equilibrium flow; Estuaries; Experiments; Flow system; Fluid flow; Fresh water; Freshwater; Froude number; Glaciers; Gravitational waves; Inland water environment; Laboratories; Laminar flow; Mathematical models; Meltwater; Plumes; Reynolds number; Salt; Salt wedges; Salts; Sea level; Seawater; Theory; Velocity; Water analysis
• ISSN: 0022-1120; 1469-7645
• DOI: 10.1017/jfm.2020.308

Marine-terminating glaciers, such as those along the coastline of Greenland, often release meltwater into the ocean in the form of subglacial discharge plumes. Though these plumes can dramatically alter the mass loss along the front of a glacier, the conditions surrounding their genesis remain poorly constrained. In particular, little is known about the geometry of subglacial outlets and the extent to which seawater may intrude into them. Here, the latter is addressed by exploring the dynamics of an arrested salt wedge – a steady-state, two-layer flow system where salty water partially intrudes a channel carrying fresh water. Building on existing theory, we formulate a model that predicts the length of a non-entraining salt wedge as a function of the Froude number, the slope of the channel and coefficients for interfacial and wall drag. In conjunction, a series of laboratory experiments were conducted to observe a salt wedge within a rectangular channel. For experiments conducted with laminar flow (Reynolds number $Re