Horizontal transport under wind-induced resonance in stratified waterbodies

Ulloa, Hugo N.; Constantinescu, George; Chang, Keun Sick; Munoz, Daniel Horna; Hames, Océane; Wüest, Alfred

doi:10.1103/physrevfluids.5.054503

Cited by 6 publications

(13 citation statements)

References 61 publications

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“…In dense hydrophyte stands, DO input from the atmosphere can be limited to the surficial layer of the water column, as long stems constitute a physical barrier, as floating-leaved macrophytes do [ 13 ]. In our case, the occurrence of a vertical “plant wall” at the external boundaries of vegetated stands may also lead to the annihilation of the horizontal flow of nutrients and DO from the pelagic to the littoral zones [ 22 ].…”

Section: Discussionmentioning

confidence: 99%

“…This can affect or, inversely, exacerbate the thermally driven exchange flow of nutrients and DO between pelagic and littoral zones of the lake [ 21 ]. Nevertheless, it has been assessed that wind episodes may induce surface and internal flows even within stratified waters [ 22 ]. Shallow lakes are continuously subjected to mixing and wave-breaking in function of wind speed [ 21 ]; in function of the lake size, slope and bathymetry, wind-exposed lakes are also concerned by periodic seiche events which contribute to water mixing [ 23 , 24 ].…”

Section: Introductionmentioning

confidence: 99%

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Wind Exposure Regulates Water Oxygenation in Densely Vegetated Shallow Lakes

Ribaudo

Tison‐Rosebery

Éon

et al. 2021

Plants

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The presence of dense macrophyte canopies in shallow lakes locally generates thermal stratification and the buildup of labile organic matter, which in turn stimulate the biological oxygen demand. The occurrence of hypoxic conditions may, however, be buffered by strong wind episodes, which favor water mixing and reoxygenation. The present study aims at explicitly linking the wind action and water oxygenation within dense hydrophytes stands in shallow lakes. For this purpose, seasonal 24 h-cycle campaigns were carried out for dissolved gases and inorganic compounds measurements in vegetated stands of an oligo-mesotrophic shallow lake. Further, seasonal campaigns were carried out in a eutrophic shallow lake, at wind-sheltered and -exposed sites. Overall results showed that dissolved oxygen (DO) daily and seasonal patterns were greatly affected by the degree of wind exposure. The occurrence of frequent wind episodes favored the near-bottom water mixing, and likely facilitated mechanical oxygen supply from the atmosphere or from the pelagic zone, even during the maximum standing crop of plants (i.e., summer and autumn). A simple model linking wind exposure (Keddy Index) and water oxygenation allowed us to produce an output management map, which geographically identified wind-sheltered sites as the most subjected to critical periods of hypoxia.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Wind Exposure Regulates Water Oxygenation in Densely Vegetated Shallow Lakes

Ribaudo

Tison‐Rosebery

Éon

et al. 2021

Plants

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“…Fricker & Nepf 2000). More recently, Ulloa et al (2019Ulloa et al ( , 2020 employed large-eddy simulation (LES) to study the hydrodynamics of a full-scale lake. In Ulloa et al (2019) a case-study investigation was conducted for the summer conditions in Lake Alpnach, Switzerland.…”

Section: Introductionmentioning

confidence: 99%

“…Besides the wave analysis, they investigated turbulence and mixing and identified episodic mixing at the sloped walls as a significant factor in overall mixing. In Ulloa et al (2020) different resonant wave responses (quasi-linear V1H1, V2H1 and nonlinear V2H1) to periodic forcing were obtained by varying the level of stratification in a three-layer stratified basin with sloping walls. The main focus of their investigation was the analysis of transport processes under the fully developed resonant wave regimes.…”

Section: Introductionmentioning

confidence: 99%

“…Similarly, we use LES to analyse the wave responses of a basin to periodic wind stress, mainly focusing on the influence of variations of forcing and bathymetry at a laboratory scale. The general set-up of our simulations is similar to that of Ulloa et al (2020) in that we apply periodic stress to a three-layer stratified domain with sloped walls; however, the focus of our research is substantially different, since we inspect the initial development of the wave response. This is an important issue, since in real systems often the wind stress regime does not allow a steady arrangement of the internal wave system, which, rather, often moves through successive transitional states.…”

Section: Introductionmentioning

confidence: 99%

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Laboratory-scale investigation of a periodically forced stratified basin with inclined endwalls

Marković

Armenio

2021

J. Fluid Mech.

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We present results of numerical simulations of a stratified reservoir with a three-layer stratification, subject to an oscillating surface shear stress. We investigate the effect of sloped endwalls on mixing and internal wave adjustment to forcing within the basin, for three different periods of forcing. The simulations are carried out at a laboratory scale, using large-eddy simulation. We solve the three-dimensional Navier–Stokes equations under the Boussinesq approximation using a second-order-accurate finite-volume solver. The model was validated by reproducing experimental results for the response of a reservoir to surface shear stress and resonant frequencies of internal waves. We find interesting combinations of wave modes and mixing under variation of the forcing frequencies and of the inclination of the endwalls. When the frequency of the forcing is close to the fundamental mode-one wave frequency, a resonant internal seiche occurs and the response is characterized by the first vertical mode. For forcing periods twice and three times the fundamental period, the dominant response is in terms of the second vertical mode. Adjustment to forcing via the second vertical mode is accompanied by the cancellation of the fundamental wave and energy transfer to higher-frequency waves. The study shows that the slope of the endwalls dramatically affects the location of mixing, which has a feedback on the wave field by promoting the generation of higher vertical modes.

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Internal wave resonance, surges, and strong nonlinear damping differentiated in two elongated lakes with the aid of an original Green's function

Long,

Halfman,

Hawley

2024

Limnology & Oceanography

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While the analogy between the wind‐pumped internal seiche in a lake and the driven damped‐harmonic oscillator is recognized, use of a damped‐oscillator model to understand internal‐wave behavior is seldom attempted due to the irregular waveforms arising from variable winds, and to the presence of nonlinear waves like surges. Using a new variable‐frequency Green's function derived for a damped oscillator within the context of the two‐layer model of a stratified basin, we examine internal wave behaviors in Seneca and Owasco Lakes, two elongated lakes in New York state with very different lengths and depths. Our approach reproduces the measured undulations of the lowest horizonal‐mode internal‐seiche with surprising fidelity. It also yields the seiche's seasonal variation of frequency, primarily due to changes in the stratification intensity and thermocline depth. Notably, our model also estimates the seiche amplitude decay‐time, a key quantity difficult to obtain for a constantly agitated seiche. The decay time matches the computed surge‐formation time, which limits seiche lifetimes to as little as one seiche period. Surges also strongly affect the undulating internal‐wave waveforms in a manner consistent with tank experiments. Finally, we find that the internal seiche in Owasco Lake exhibits a uniquely well‐defined resonance with the diel wind pattern, and, for Seneca Lake, that surges propagate bidirectionally, augmenting an oft‐cited report of surges traveling only in one direction.

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Horizontal transport under wind-induced resonance in stratified waterbodies

Cited by 6 publications

References 61 publications

Wind Exposure Regulates Water Oxygenation in Densely Vegetated Shallow Lakes

Wind Exposure Regulates Water Oxygenation in Densely Vegetated Shallow Lakes

Laboratory-scale investigation of a periodically forced stratified basin with inclined endwalls

Internal wave resonance, surges, and strong nonlinear damping differentiated in two elongated lakes with the aid of an original Green's function

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