Quantifying propagation characteristics of unconfined turbidity currents interacting with an obstacle within the slumping regime

ABSTRACT

Experimental studies of confined turbidity currents interacting with obstacles have become popular over the last three decades; however, little work has sought to quantify the characteristics of unconfined turbidity currents interacting with obstacles. In the present study, unconfined turbidity currents colliding with a rectangular basal obstruction are investigated. With a focus on the initial theoretical slumping regime, flow characteristics are quantified and characterized. The currents varied with initial density and substrate roughness. Unobstructed currents propagated at a constant velocity, confirming previous theory that the current is within the slumping regime; however, a typical reverse ambient bore was not present. Froude and Reynolds numbers were shown to decrease over the obstacle by 43–54% and 17%, respectively. Deflected lateral propagation along the obstacle face was found to entrap ambient fluid and encourage mixing, providing a starting point for understanding the implications of lateral propagation along submerged pipelines and reservoir barriers.

Keywords:

• Instability
• obstacle
• sediment-laden flow
• unconfined
• visualization

Acknowledgements

We would like to thank Trevor Patrick, Geoff Kirby and Jim Luo for their help in constructing and installing required experimental components.

ORCID

Richard I Wilson http://orcid.org/0000-0001-6613-3760

Heide Friedrich http://orcid.org/0000-0002-6419-5973

Craig Stevens http://orcid.org/0000-0002-4730-6985