Interaction of a mode-2 internal solitary wave with narrow isolated topography

TY - JOUR

T1 - Interaction of a mode-2 internal solitary wave with narrow isolated topography

AU - Deepwell, David

AU - Stastna, Mark

AU - Carr, Magdalen

AU - Davies, Peter

N1 - This research was supported by the Natural Sciences and Engineering Research Council of Canada through a Discovery Grant (MS) and the Government of Ontario through a Queen Elizabeth II Graduate Scholarship in Science and Technology (DD). The experimental work was conducted at the University of Dundee by D.D. and M.C. with the aid of grants provided by the University of Dundee, the University of St Andrews, and the University of Waterloo. Much appreciation is reserved for the technical assistance provided by John Anderson and David Turbyne. The authors would also like to acknowledge the helpful feedback given by two anonymous referees.

PY - 2017/7/31

Y1 - 2017/7/31

N2 - Numerical and experimental studies of the transit of a mode-2 internal solitary wave over an isolated ridge are presented. All studies used a quasi-two-layer fluid with a pycnocline centred at the middepth. The wave amplitude and total fluid depth were both varied, while the topography remained fixed. The strength of the interaction between the internal solitary waves and the hill was found to be characterized by three regimes: weak, moderate, and strong interactions. The weak interaction exhibited negligible wave modulation and bottom surface stress. The moderate interaction generated weak and persistent vorticity in the lower layer, in addition to negligible wave modulation. The strong interaction clearly showed material from the trapped core of the mode-2 wave extracted in the form of a thin filament while generating a strong vortex at the hill. A criterion for the strength of the interaction was found by non-dimensionalizing the wave amplitude by the lower layer depth, a/`. A passive tracer was used to measure the conditions for resuspension of boundary material due to the interaction. The speed and prevalence of cross boundary layer transport increased with a/`. Published by AIP Publishing.

AB - Numerical and experimental studies of the transit of a mode-2 internal solitary wave over an isolated ridge are presented. All studies used a quasi-two-layer fluid with a pycnocline centred at the middepth. The wave amplitude and total fluid depth were both varied, while the topography remained fixed. The strength of the interaction between the internal solitary waves and the hill was found to be characterized by three regimes: weak, moderate, and strong interactions. The weak interaction exhibited negligible wave modulation and bottom surface stress. The moderate interaction generated weak and persistent vorticity in the lower layer, in addition to negligible wave modulation. The strong interaction clearly showed material from the trapped core of the mode-2 wave extracted in the form of a thin filament while generating a strong vortex at the hill. A criterion for the strength of the interaction was found by non-dimensionalizing the wave amplitude by the lower layer depth, a/`. A passive tracer was used to measure the conditions for resuspension of boundary material due to the interaction. The speed and prevalence of cross boundary layer transport increased with a/`. Published by AIP Publishing.

KW - Internal waves

KW - Geodesy

KW - Vector calculus

KW - Turbulent flows

KW - Oceanography

U2 - 10.1063/1.4994590

DO - 10.1063/1.4994590

M3 - Article

SN - 1070-6631

VL - 29

JO - Physics of Fluids

JF - Physics of Fluids

IS - 7

M1 - 076601

ER -