Internal hydraulic jumps in two-layer flows with upstream shear

Ogden, Kelly; Helfrich, Karl R.

doi:10.1017/jfm.2015.727

Cited by 17 publications

(20 citation statements)

References 39 publications

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“…1 show that the jumps extend over moderate slopes, yet because alongfront variability is neglected here, increasing model complexity by calculating nonlinear internal bore celerities using depth-resolved stratification does not necessarily coincide with additional accuracy. We note that a large-amplitude head can occur for even relatively small jumps in the presence of upstream shear (Klemp et al 1997;Ogden and Helfrich 2016), as is the case for J1 and J2. The observed jump angles lie within the expected bounds described in section 2 (u 0 , u , u b ).…”

Section: January 2017 H O N E G G E R E T a Lmentioning

confidence: 56%

“…In a Boussinesq fluid, this solution approximately corresponds to the maximum celerity bore (White and Helfrich 2014;Ogden and Helfrich 2016;Baines 2016). The angle u of an oblique, internal hydraulic jump in a two-layer, inviscid, FIG.…”

Section: Oblique Hydraulic Jumpsmentioning

confidence: 95%

“…Although some effects of finite interface thickness and upstream vertical shear on the internal bore speed have recently been documented (White and Helfrich 2014;Ogden and Helfrich 2016), details of a combination of the two remain poorly understood. The Taylor-Goldstein equation (e.g., Miles 1961) resolves such continuous vertical structure, and estimated jump angles corresponding to normal-mode phase speed solutions of the equation (Kundu and Cohen 2004;Smyth et al 2011) are shown in Figs.…”

Section: January 2017 H O N E G G E R E T a Lmentioning

confidence: 99%

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Oblique Internal Hydraulic Jumps at a Stratified Estuary Mouth

Honegger

Haller

Geyer

et al. 2017

Journal of Physical Oceanography

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Observations and analyses of two tidally recurring, oblique, internal hydraulic jumps at a stratified estuary mouth (Columbia River, Oregon/Washington) are presented. These hydraulic features have not previously been studied due to the challenges of both horizontally resolving the sharp gradients and temporally resolving their evolution in numerical models and traditional observation platforms. The jumps, both of which recurred during ebb, formed adjacent to two engineered lateral channel constrictions and were identified in marine radar image time series. Jump occurrence was corroborated by (i) a collocated sharp gradient in the surface currents measured via airborne along-track interferometric synthetic aperture radar and (ii) the transition from supercritical to subcritical flow in the cross-jump direction via shipborne velocity and density measurements. Using a two-layer approximation, observed jump angles at both lateral constrictions are shown to lie within the theoretical bounds given by the critical internal long-wave (Froude) angle and the arrested maximum-amplitude internal bore angle, respectively. Also, intratidal and intertidal variability of the jump angles are shown to be consistent with that expected from the two-layer model, applied to varying stratification and current speed over a range of tidal and river discharge conditions. Intratidal variability of the upchannel jump angle is similar under all observed conditions, whereas the downchannel jump angle shows an additional association with stratification and ebb velocity during the low discharge periods. The observations additionally indicate that the upchannel jump achieves a stable position that is collocated with a similarly oblique bathymetric slope.

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Section: January 2017 H O N E G G E R E T a Lmentioning

confidence: 56%

Section: Oblique Hydraulic Jumpsmentioning

confidence: 95%

Section: January 2017 H O N E G G E R E T a Lmentioning

confidence: 99%

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Oblique Internal Hydraulic Jumps at a Stratified Estuary Mouth

Honegger

Haller

Geyer

et al. 2017

Journal of Physical Oceanography

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“…Therefore, a hydraulic jump formed as a result of the transition of the freshened flow from the supercritical near-field plume to the subcritical far-field plume generated IW, which were detected by satellite imagery and in situ measurements. A number of previous studies addressed generation of IW by a hydraulic jump in a two-layered fluid 30 , 31 . A schematic diagram of this process occurring in a river plume is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Small Mountainous Rivers Generate High-Frequency Internal Waves in Coastal Ocean

Osadchiev

2018

Sci Rep

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High-frequency internal waves propagating offshore in small river plumes are regularly observed at satellite imagery in many world regions. In this work we describe a mechanism of generation of these internal waves by discharges of small and rapid rivers inflowing to coastal sea. Friction between river runoff at high velocity and the subjacent sea of one order of magnitude lower velocity causes abrupt deceleration of a freshened flow and increase of its depth, i.e., a hydraulic jump is formed. Transition from supercritical to subcritical flow conditions induces generation of high-frequency internal waves that propagate off a river mouth at a stratified layer between a buoyant river plume and subjacent ambient sea and influence turbulence and mixing at this layer. Basing on in situ and satellite data we estimated wavelengths, phase speeds, and frequencies of internal waves generated in small river plumes located off the northeastern coast of the Black Sea. This process is typical for many other world mountainous regions where numerous and closely spaced small and rapid rivers inflow to sea during high discharge periods and can strongly influence, first, structure and dynamics of river plumes and, second, physical, biological, and geochemical processes in adjacent coastal areas.

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“…A stratified layer in which the jump occurs flows over a rigid horizontal boundary at z = 0 and beneath a uniform stationary fluid of infinite depth. Unlike the majority of models of such jumps which assume that the flow consists of two discrete uniform layers upstream of the hydraulic transition (reviewed, for example, by Ogden &Helfrich, 2016, andBaines, 2016), TL adopt continuous profiles of velocity and density both upstream and downstream of the transition. The velocities in the model are given by…”

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confidence: 99%

Application of a model of internal hydraulic jumps

et al. 2017

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A model devised by Thorpe & Li (J. Fluid Mech., vol. 758, 2014, pp. 94–120) that predicts the conditions in which stationary turbulent hydraulic jumps can occur in the flow of a continuously stratified layer over a horizontal rigid bottom is applied to, and its results compared with, observations made at several locations in the ocean. The model identifies two positions in the Samoan Passage at which hydraulic jumps should occur and where changes in the structure of the flow are indeed observed. The model predicts the amplitude of changes and the observed mode 2 form of the transitions. The predicted dissipation of turbulent kinetic energy is also consistent with observations. One location provides a particularly well-defined example of a persistent hydraulic jump. It takes the form of a 390 m thick and 3.7 km long mixing layer with frequent density inversions separated from the seabed by some 200 m of relatively rapidly moving dense water, thus revealing the previously unknown structure of an internal hydraulic jump in the deep ocean. Predictions in the Red Sea Outflow in the Gulf of Aden are relatively uncertain. Available data, and the model predictions, do not provide strong support for the existence of hydraulic jumps. In the Mediterranean Outflow, however, both model and data indicate the presence of a hydraulic jump.

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Internal hydraulic jumps in two-layer flows with upstream shear

Cited by 17 publications

References 39 publications

Oblique Internal Hydraulic Jumps at a Stratified Estuary Mouth

Oblique Internal Hydraulic Jumps at a Stratified Estuary Mouth

Small Mountainous Rivers Generate High-Frequency Internal Waves in Coastal Ocean

Application of a model of internal hydraulic jumps

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