Large amplitude internal waves in naturally occurring stratified fluids induce currents throughout the water column and hence have the potential to drive instability, and turbulent transition within, and hence material exchange across the bottom boundary layer. In the presence of broad, small amplitude topography, waves of depression have been shown to induce a vortex roll-up instability that has the potential for cross-bottom boundary layer transport through the generation of coherent vortices. At the same time, the three-dimensionalization associated with the instability is weak. We demonstrate that the presence of a near-bottom stratification provides a means for an enhanced rate of three-dimensionalization. For solitary waves of elevation, which do not yield a coherent response in the absence of a near-bottom stratification, the presence of a near-bottom stratification leads to a local hydraulic response, or a gravity-current-like intrusion, as the wave passes over the topography. This feature forms on the lee slope of the topography, propagates with the wave for some time, and provides a coherent pathway for material to be transported a distance of 1.5 times the topography amplitude into the water column in laboratory-scale simulations. Evidence of coherent structures in the turbulent flow in this region is presented.
REFERENCES
1.
E.
Shroyer
, J.
Moum
, and J.
Nash
, “Observations of polarity reversal in shoaling nonlinear internal waves
,” J. Phys. Oceanogr.
39
, 691
–701
(2009
).2.
D.
Bogucki
, T.
Dickey
, and L. G.
Redekopp
, “Sediment resuspension and mixing by resonantly generated internal solitary waves
,” J. Phys. Oceanogr.
27
, 1181
–1196
(1997
).3.
V.
Maderich
, T.
Talipova
, R.
Grimshaw
, K.
Terletska
, I.
Brovchenko
, E.
Pelinovsky
, and B. H.
Choi
, “Interaction of a large amplitude interfacial solitary wave of depression with a bottom step
,” Phys. Fluids
22
, 076602
(2010
).4.
T.
Talipova
, K.
Terletska
, V.
Maderich
, I.
Brovchenko
, K. T.
Jung
, E.
Pelinovsky
, and R.
Grimshaw
, “Internal solitary wave transformation over a bottom step: Loss of energy
,” Phys. Fluids
25
, 032110
(2013
).5.
P. G.
Baines
, “Mixing in downslope flows in the ocean-plumes versus gravity currents
,” Atmos.-Ocean
46
, 405
–419
(2008
).6.
N. J.
Baeten
, J. S.
Laberg
, M.
Forwick
, T. O.
Vorren
, M.
Vanneste
, C. F.
Forsberg
, T. J.
Kvalstad
, and M.
Ivanov
, “Morphology and origin of smaller-scale mass movements on the continental slope off northern Norway
,” Geomorphology
187
, 122
–134
(2013
).7.
R.
Porter-Smith
, V.
Lyne
, R.
Kloser
, and V.
Lucieer
, “Catchment-based classification of Australia’s continental slope canyons
,” Mar. Geol.
303
, 183
–192
(2012
).8.
D.
Cacchione
and L.
Pratson
, “Internal tides and the continental slope curious waves coursing beneath the surface of the sea may shape the margins of the world’s landmasses
,” Am. Sci.
92
, 130
–137
(2004
).9.
M. E.
Tucker
, Sedimentary Petrology: An Introduction to the Origin of Sedimentary Rocks
(John Wiley & Sons
, 2009
), pp. 80
–81
.10.
S.
Albarracín
, J.
Alcántara-ió
, I.
Montoya-Montes
, Á.
Fontán-Bouzas
, L.
Somoza
, C. L.
Amos
, and J. R.
Salgado
, “Relict sand waves in the continental shelf of the gulf of Valencia (western Mediterranean)
,” J. Sea Res.
93
, 33
–46
(2014
).11.
R. D.
Flood
, A. N.
Shor
, and P. L.
Manley
, “Morphology of abyssal MUDWAVES at project MUDWAVES sites in the Argentine basin
,” Deep Sea Res., Part II
40
, 859
–888
(1993
).12.
S.
Harnanan
, N.
Soontiens
, and M.
Stastna
, “Internal wave boundary layer interaction: A novel instability over broad topography
,” Phys. Fluids
27
, 016605
(2015
).13.
P. J.
Diamessis
and L. G.
Redekopp
, “Numerical investigation of solitary internal wave-induced global instability in shallow water benthic boundary layers
,” J. Phys. Oceanogr.
36
, 784
–812
(2006
).14.
M.
Carr
, P. A.
Davies
, and P.
Shivaram
, “Experimental evidence of internal solitary wave-induced global instability in shallow water benthic boundary layers
,” Phys. Fluids
20
, 066603
(2008
).15.
M.
Stastna
and K. G.
Lamb
, “Sediment resuspension mechanisms associated with internal waves in coastal waters
,” J. Geophys. Res.: Oceans
113
, C10016
, doi:10.1029/2007jc004711 (2008
).16.
M.
Carr
and P.
Davies
, “Boundary layer flow beneath an internal solitary wave of elevation
,” Phys. Fluids
22
, 026601
(2010
).17.
P.
Aghsaee
and L.
Boegman
, “Experimental investigation of sediment resuspension beneath internal solitary waves of depression
,” J. Geophys. Res.: Oceans
120
, 3301
–3314
, doi:10.1002/2014jc010401 (2015
).18.
L. S.
Quaresma
, J.
Vitorino
, A.
Oliveira
, and J.
da Silva
, “Evidence of sediment resuspension by nonlinear internal waves on the western Portuguese mid-shelf
,” Mar. Geol.
246
, 123
–143
(2007
).19.
J.
Olsthoorn
and M.
Stastna
, “Numerical investigation of internal wave-induced sediment motion: Resuspension versus entrainment
,” Geophys. Res. Lett.
41
, 2876
–2882
, doi:10.1002/2014gl059826 (2014
).20.
C.
Scalo
, U.
Piomelli
, and L.
Boegman
, “High-Schmidt-number mass transport mechanisms from a turbulent flow to absorbing sediments
,” Phys. Fluids
24
, 085103
(2012
).21.
I.
McCave
, “Local and global aspects of the bottom nepheloid layers in the world ocean
,” Neth. J. Sea Res.
20
, 167
–181
(1986
).22.
N.
Hawley
and R. W.
Muzzi
, “Observations of nepheloid layers made with an autonomous vertical profiler
,” J. Great Lakes Res.
29
, 124
–133
(2003
).23.
N. D.
Graham
, S.
Stoll
, and J.-L.
Loizeau
, “Colloid characterization at the sediment-water interface of Vidy Bay, Lake Geneva
,” Fundam. Appl. Limnol./Arch. Hydrobiol.
184
, 87
–100
(2014
).24.
P.
Jones
, K.
Maiti
, and J.
McManus
, “Lead-210 and polonium-210 disequilibria in the northern gulf of Mexico hypoxic zone
,” Mar. Chem.
169
, 1
–15
(2015
).25.
C.
Pilskaln
, K.
Hayashi
, B.
Keafer
, D.
Anderson
, and D.
McGillicuddy
, “Benthic nepheloid layers in the Gulf of Maine and Alexandrium cyst inventories
,” Deep Sea Res., Part II
103
, 55
–65
(2014
).26.
J. E.
Baker
, S. J.
Eisenreich
, and B. J.
Eadie
, “Sediment trap fluxes and benthic recycling of organic carbon, polycyclic aromatic hydrocarbons, and polychlorobiphenyl congeners in Lake Superior
,” Environ. Sci. Technol.
25
, 500
–509
(1991
).27.
A.
Mudroch
and P.
Mudroch
, “Geochemical composition of the nepheloid layer in Lake Ontario
,” J. Great Lakes Res.
18
, 132
–153
(1992
).28.
N. R.
Urban
, J.
Jeong
, and Y.
Chai
, “The benthic nepheloid layer (BNL) north of the Keweenaw Peninsula in Lake Superior: Composition, dynamics, and role in sediment transport
,” J. Great Lakes Res.
30
, 133
–146
(2004
).29.
O. M.
Cheriton
, E. E.
McPhee-Shaw
, C. D.
Storlazzi
, K. J.
Rosenberger
, W. J.
Shaw
, and B. Y.
Raanan
, “Upwelling rebound, ephemeral secondary pycnoclines, and the creation of a near-bottom wave guide over the Monterey Bay continental shelf
,” Geophys. Res. Lett.
41
, 8503
–8511
, doi:10.1002/2014gl061897 (2014
).30.
B.
Turkington
, A.
Eydeland
, and S.
Wang
, “A computational method for solitary internal waves in a continuously stratified fluid
,” Stud. Appl. Math.
85
, 93
–127
(1991
).31.
M.
Dunphy
, C.
Subich
, and M.
Stastna
, “Spectral methods for internal waves: Indistinguishable density profiles and double-humped solitary waves
,” Nonlinear Processes Geophys.
18
, 351
–358
(2011
).32.
C.
Subich
, K.
Lamb
, and M.
Stastna
, “Simulation of the Navier-Stokes equations in three dimensions with a spectral collocation method
,” Int. J. Numer. Methods Fluids
73
, 103
–129
(2013
).33.
M. H.
García
, “Sedimentation and erosion hydraulics
,” in Hydraulic Design Handbook
(McGraw-Hill, Inc.
, 1999
), p. 1112
.34.
R.
Munro
, N.
Bethke
, and S.
Dalziel
, “Sediment resuspension and erosion by vortex rings
,” Phys. Fluids
21
, 046601
(2009
).35.
R. J.
Munro
, “The interaction of a vortex ring with a sloped sediment layer: Critical criteria for incipient grain motion
,” Phys. Fluids
24
, 026604
(2012
).36.
P. K.
Kundu
, I. M.
Cohen
, and D. R.
Dowling
, Fluid Mechanics
, 5th ed. (Academic Press
, 2012
).37.
M.
Kadosch
, “The curved wall effect
,” in Proceedings of 2nd Cranfield Fluidics Conference
, Cambridge
, 1967
.38.
B. G.
Newman
, “The deflection of plane jets by adjacent boundaries - Coanda effect
,” Boundary Layer Flow Control
1
, 232
–264
(1961
).39.
P.
Bradshaw
, “Effects of streamline curvature on turbulent flow
,” Technical Reports
(DTIC Document
, 1973
).40.
J. E.
Simpson
, Gravity Currents: In the Environment and the Laboratory
, 2nd ed. (Cambridge University Press
, 1997
).41.
A. G.
Lawrie
and S. B.
Dalziel
, “Turbulent diffusion in tall tubes. I. Models for Rayleigh-Taylor instability
,” Phys. Fluids
23
, 085109
(2011
).42.
M. J.
Andrews
and S. B.
Dalziel
, “Small Atwood number Rayleigh–Taylor experiments
,” Philos. Trans. R. Soc., A
368
, 1663
–1679
(2010
).43.
C.
Härtel
, E.
Meiburg
, and F.
Necker
, “Analysis and direct numerical simulation of the flow at a gravity-current head. Part 1. Flow topology and front speed for slip and no-slip boundaries
,” J. Fluid Mech.
418
, 189
–212
(2000
).44.
C.
Hartel
, F.
Carlsson
, and M.
Thunblom
, “Analysis and direct numerical simulation of the flow at a gravity-current head. Part 2. The lobe-and-cleft instability
,” J. Fluid Mech.
418
, 213
–229
(2000
).45.
P.
Holmes
, J. L.
Lumley
, and G.
Berkooz
, Turbulence, Coherent Structures, Dynamical Systems and Symmetry
(Cambridge University Press
, 1998
).46.
J.
Jeong
and F.
Hussain
, “On the identification of a vortex
,” J. Fluid Mech.
285
, 69
–94
(1995
).47.
K.
Christensen
and R. J.
Adrian
, “Statistical evidence of hairpin vortex packets in wall turbulence
,” J. Fluid Mech.
431
, 433
–443
(2001
).48.
N.
Hawley
and C.
Murthy
, “The response of the benthic nepheloid layer to a downwelling event
,” J. Great Lakes Res.
21
, 641
–651
(1995
).© 2016 Author(s).
2016
Author(s)
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