Статті в журналах: "Depth-induced breaking"

1

Salmon, J. E., and L. H. Holthuijsen. "Modeling depth-induced wave breaking over complex coastal bathymetries." Coastal Engineering 105 (November 2015): 21–35. http://dx.doi.org/10.1016/j.coastaleng.2015.08.002.

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2

Salmon, J. E., L. H. Holthuijsen, M. Zijlema, G. Ph van Vledder, and J. D. Pietrzak. "Scaling depth-induced wave-breaking in two-dimensional spectral wave models." Ocean Modelling 87 (March 2015): 30–47. http://dx.doi.org/10.1016/j.ocemod.2014.12.011.

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3

Smit, Pieter, Marcel Zijlema, and Guus Stelling. "Depth-induced wave breaking in a non-hydrostatic, near-shore wave model." Coastal Engineering 76 (June 2013): 1–16. http://dx.doi.org/10.1016/j.coastaleng.2013.01.008.

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4

FRUCTUS, DORIAN, MAGDA CARR, JOHN GRUE, ATLE JENSEN, and PETER A. DAVIES. "Shear-induced breaking of large internal solitary waves." Journal of Fluid Mechanics 620 (February 10, 2009): 1–29. http://dx.doi.org/10.1017/s0022112008004898.

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The stability properties of 24 experimentally generated internal solitary waves (ISWs) of extremely large amplitude, all with minimum Richardson number less than 1/4, are investigated. The study is supplemented by fully nonlinear calculations in a three-layer fluid. The waves move along a linearly stratified pycnocline (depth h2) sandwiched between a thin upper layer (depth h1) and a deep lower layer (depth h3), both homogeneous. In particular, the wave-induced velocity profile through the pycnocline is measured by particle image velocimetry (PIV) and obtained in computation. Breaking ISWs were found to have amplitudes (a1) in the range $a_1\,{>}\,2.24\sqrt{h_1h_2}(1+h_2/h_1)$, while stable waves were on or below this limit. Breaking ISWs were investigated for 0.27 < h2/h1 < 1 and 4.14 < h3/(h1 + h2) < 7.14 and stable waves for 0.36 < h2/h1 < 3.67 and 3.22 < h3/(h1 + h2) < 7.25. Kelvin–Helmholtz-like billows were observed in the breaking cases. They had a length of 7.9h2 and a propagation speed 0.09 times the wave speed. These measured values compared well with predicted values from a stability analysis, assuming steady shear flow with U(z) and ρ(z) taken at the wave maximum (U(z) horizontal velocity profile, ρ(z) density along the vertical z). Only unstable modes in waves of sufficient strength have the chance to grow sufficiently fast to develop breaking: the waves that broke had an estimated growth (of unstable modes) more than 3.3–3.7 times than in the strongest stable case. Evaluation of the minimum Richardson number (Rimin, in the pycnocline), the horizontal length of a pocket of possible instability, with wave-induced Ri < 14, (Lx) and the wavelength (λ), showed that all measurements fall within the range Rimin = −0.23Lx/λ + 0.298 ± 0.016 in the (Lx/λ, Rimin)-plane. Breaking ISWs were found for Lx/λ > 0.86 and stable waves for Lx/λ < 0.86. The results show a sort of threshold-like behaviour in terms of Lx/λ. The results demonstrate that the breaking threshold of Lx/λ = 0.86 was sharper than one based on a minimum Richardson number and reveal that the Richardson number was found to become almost antisymmetric across relatively thick pycnoclines, with the minimum occurring towards the top part of the pycnocline.

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5

Hieu, Phung Dang, and Phan Ngoc Vinh. "A numerical model for simulation of near-shore waves and wave induced currents using the depth-averaged non-hydrostatic shallow water equations with an improvement of wave energy dissipation." Tạp chí Khoa học và Công nghệ biển 20, no. 2 (May 22, 2020): 155–72. http://dx.doi.org/10.15625/1859-3097/20/2/15087.

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This study proposes a numerical model based on the depth-integrated non-hydrostatic shallow water equations with an improvement of wave breaking dissipation. Firstly, studies of parameter sensitivity were carried out using the proposed numerical model for simulation of wave breaking to understand the effects of the parameters of the breaking model on wave height distribution. The simulated results of wave height near the breaking point were very sensitive to the time duration parameter of wave breaking. The best value of the onset breaking parameter is around 0.3 for the non-hydrostatic shallow water model in the simulation of wave breaking. The numerical results agreed well with the published experimental data, which confirmed the applicability of the present model to the simulation of waves in near-shore areas.

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6

Kuznetsov, Sergey, Yana Saprykina, and Valentina Volkova. "DEPENDENCIES OF BREAKING TYPE, BREAKING CRITERIA AND ENERGY DISSIPATION ON AMPLITUDE-PHASE FREQUENCY STRUCTURE OF WAVES." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 72. http://dx.doi.org/10.9753/icce.v36.papers.72.

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Type of wave breaking - plunging or spilling - depends on symmetry of waves. The spilling waves are asymmetric against horizontal axis and are practically symmetric against vertical axis so the phase shift between first and second nonlinear harmonics (or biphase) is close to zero. The plunging breaking waves have larger asymmetry against vertical axis, (biphase is close to -pi/2), and near symmetric on horizontal axis (close to saw-toothed form). Non-linear wave transformation influences on depth-induced wave breaking. Breaking index depends on relation of wave energy in frequency range of second nonlinear harmonics to wave energy in frequency range of main harmonic and on biphase. The dissipation rate of spilling breaking waves energy quadratically depends on frequency, while in plunging breaking, this dependency is practically linear for all frequencies.

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7

Chen, Zereng, Qinghe Zhang, Yongsheng Wu, and Chao Ji. "A modified breaker index formula for depth-induced wave breaking in spectral wave models." Ocean Engineering 264 (November 2022): 112527. http://dx.doi.org/10.1016/j.oceaneng.2022.112527.

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8

Draycott, S., Y. Li, P. K. Stansby, T. A. A. Adcock, and T. S. van den Bremer. "Harmonic-induced wave breaking due to abrupt depth transitions: An experimental and numerical study." Coastal Engineering 171 (January 2022): 104041. http://dx.doi.org/10.1016/j.coastaleng.2021.104041.

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9

Seyed Alipur, Seyed Ali, Seyed Mostafa Siadatmousavi, and Seyed Masoud Mahmoudof. "Improving the Simulation of Depth-induced Breaking in the Third-Generation Wave Model SWAN." مهندسی دریا 16, no. 31 (April 1, 2020): 53–64. http://dx.doi.org/10.29252/marineeng.16.31.53.

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10

Deike, Luc, Nick Pizzo, and W. Kendall Melville. "Lagrangian transport by breaking surface waves." Journal of Fluid Mechanics 829 (September 19, 2017): 364–91. http://dx.doi.org/10.1017/jfm.2017.548.

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The Lagrangian transport due to non-breaking and breaking focusing wave packets is examined. We present direct numerical simulations of the two-phase air–water Navier–Stokes equations describing focusing wave packets, investigating the Lagrangian drift by tracking tracer particles in the water before, during and after the breaking event. The net horizontal transport for non-breaking focusing packets is well described by the classical Stokes drift, both at the surface and in the bulk of the fluid, where the e-folding scale of the evanescent vertical profile is given by the characteristic wavenumber. For focusing wave packets that lead to breaking, we observe an added drift that can be ten times larger than the classical Stokes drift for a non-breaking packet at the surface, while the initial depth of the broken fluid scales with the wave height at breaking. We find that the breaking induced Lagrangian transport scales with the breaking strength. A simple scaling argument is proposed to describe this added drift and is found to be consistent with the direct numerical simulations. Applications to upper ocean processes are discussed.

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11

Mares-Nasarre, Patricia, Gloria Argente, M. Esther Gómez-Martín, and Josep R. Medina. "Armor Damage of Overtopped Mound Breakwaters in Depth-Limited Breaking Wave Conditions." Journal of Marine Science and Engineering 9, no. 9 (September 1, 2021): 952. http://dx.doi.org/10.3390/jmse9090952.

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Armor damage due to wave attack is the principal failure mode to be considered when designing conventional mound breakwaters. Armor layers of mound breakwaters are typically designed using formulas in the literature for non-overtopped mound breakwaters in non-breaking wave conditions, although overtopped mound breakwaters in the depth-induced breaking wave zone are common design conditions. In this study, 2D physical tests with an armor slope H/V = 3/2 are analyzed in order to better describe the hydraulic stability of overtopped mound breakwaters with double-layer rock, double-layer randomly-place cube and single-layer Cubipod® armors in depth-limited breaking wave conditions. Hydraulic stability formulas are derived for each armor section (front slope, crest and rear slope) and each armor layer. The front slope of overtopped double-layer rock structures is more stable than the front slope of non-overtopped mound breakwaters in breaking wave conditions. When wave attack increases, armor damage appears first on the front slope, later on the crest and, finally, on the rear side. However, once the damage begins on the crest and rear side, the progression is much faster than on the front slope, because more wave energy is dissipated through the armored crest and rear side.

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12

Feddersen, Falk, J. H. Trowbridge, and A. J. Williams. "Vertical Structure of Dissipation in the Nearshore." Journal of Physical Oceanography 37, no. 7 (July 1, 2007): 1764–77. http://dx.doi.org/10.1175/jpo3098.1.

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Abstract The vertical structure of the dissipation of turbulence kinetic energy was observed in the nearshore region (3.2-m mean water depth) with a tripod of three acoustic Doppler current meters off a sandy ocean beach. Surface and bottom boundary layer dissipation scaling concepts overlap in this region. No depth-limited wave breaking occurred at the tripod, but wind-induced whitecapping wave breaking did occur. Dissipation is maximum near the surface and minimum at middepth, with a secondary maximum near the bed. The observed dissipation does not follow a surfzone scaling, nor does it follow a “log layer” surface or bottom boundary layer scaling. At the upper two current meters, dissipation follows a modified deep-water breaking-wave scaling. Vertical shear in the mean currents is negligible and shear production magnitude is much less than dissipation, implying that the vertical diffusion of turbulence is important. The increased near-bed secondary dissipation maximum results from a decrease in the turbulent length scale.

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13

Wang, Haili, Changming Dong, Yongzeng Yang, and Xiaoqian Gao. "Parameterization of Wave-Induced Mixing Using the Large Eddy Simulation (LES) (I)." Atmosphere 11, no. 2 (February 15, 2020): 207. http://dx.doi.org/10.3390/atmos11020207.

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Turbulent motions in the thin ocean surface boundary layer control exchanges of momentum, heat and trace gases between the atmosphere and ocean. However, present parametric equations of turbulent motions that are applied to global climate models result in systematic or substantial errors in the ocean surface boundary layer. Significant mixing caused by surface wave processes is missed in most parametric equations. A Large Eddy Simulation model is applied to investigate the wave-induced mixed layer structure. In the wave-averaged equations, wave effects are calculated as Stokes forces and breaking waves. To examine the effects of wave parameters on mixing, a series of wave conditions with varying wavelengths and heights are used to drive the model, resulting in a variety of Langmuir turbulence and wave breaking outcomes. These experiments suggest that wave-induced mixing is more sensitive to wave heights than to the wavelength. A series of numerical experiments with different wind intensities-induced Stokes drifts are also conducted to investigate wave-induced mixing. As the wind speed increases, the influence depth of Langmuir circulation deepens. Additionally, it is observed that breaking waves could destroy Langmuir cells mainly at the sea surface, rather than at deeper layers.

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14

Yoon, Hyun-Doug, and Daniel T. Cox. "Cross-shore variation of intermittent sediment suspension and turbulence induced by depth-limited wave breaking." Continental Shelf Research 47 (September 2012): 93–106. http://dx.doi.org/10.1016/j.csr.2012.07.001.

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15

Papoutsellis, Christos E., Marissa L. Yates, Bruno Simon, and Michel Benoit. "Modelling of depth-induced wave breaking in a fully nonlinear free-surface potential flow model." Coastal Engineering 154 (December 2019): 103579. http://dx.doi.org/10.1016/j.coastaleng.2019.103579.

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16

Babanin, Alexander V., Michael L. Banner, Ian R. Young, and Mark A. Donelan. "Wave-Follower Field Measurements of the Wind-Input Spectral Function. Part III: Parameterization of the Wind-Input Enhancement due to Wave Breaking." Journal of Physical Oceanography 37, no. 11 (November 1, 2007): 2764–75. http://dx.doi.org/10.1175/2007jpo3757.1.

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Abstract This is the third in a series of papers describing wave-follower observations of the aerodynamic coupling between wind and waves on a large shallow lake during the Australian Shallow Water Experiment (AUSWEX). It focuses on the long-standing problem of the aerodynamic consequences of wave breaking on the wind–wave coupling. Direct field measurements are reported of the influence of wave breaking on the wave-induced pressure in the airflow over water waves, and hence the energy flux to the waves. The level of forcing, measured by the ratio of wind speed to the speed of the dominant (spectral peak) waves, covered the range of 3–7. The propagation speeds of the dominant waves were limited by the water depth and the waves were correspondingly steep. These measurements allowed an assessment of the magnitude of any breaking-induced enhancement operative for these field conditions and provided a basis for parameterizing the effect. Overall, appreciable levels of wave breaking occurred for the strong wind forcing conditions that prevailed during the observational period. Associated with these breaking wave events, a significant phase shift is observed in the local wave-coherent surface pressure. This produced an enhanced wave-coherent energy flux from the wind to the waves with a mean value of 2 times the corresponding energy flux to the nonbreaking waves. It is proposed that the breaking-induced enhancement of the wind input to the waves can be parameterized by the sum of the nonbreaking input and the contribution due to the breaking probability.

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17

Shand, Thomas D., William L. Peirson, and Ronald J. Cox. "ENGINEERING DESIGN IN THE PRESENCE OF WAVE GROUPS." Coastal Engineering Proceedings 1, no. 32 (February 1, 2011): 68. http://dx.doi.org/10.9753/icce.v32.waves.68.

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Determining the largest wave height, H which can occur in water of depth, d without breaking is a fundamental reference quantity for the design of coastal structures. Current design guidelines, used to predict the ratio of breaking height to depth (Hb/d), also known as the breaker index, are based on investigations which predominantly used monochromatic waves, thereby implicitly neglecting group effects. Groupiness or height modulation in wave trains is an inherent characteristic of freely propagating waves in deep water and has been shown within previous studies to induce breaker indices substantially exceeding those predicted by design guidelines. Additionally, the raw data upon which present design guidelines have been based exhibit considerable scatter. This scatter is surprising given the monochromatic and uniform nature of the laboratory waves. A physical investigation at the Water Research Laboratory using new techniques for data extraction and visualisation has yielded new insights into the shoaling and breaking processes of regular and grouped waves and revealed deficiencies in the present design techniques. Monochromatic waves trains were found to develop amplitude modulation with distance along the flume due to non-linear instabilities. These instabilities are well recognized in deep-water waves and contribute to group development and the occurrence of low-probability extreme waves. These modulations induced variation in breaking wave heights, locations and derived breaker indices. Such modulation of initially regular wave trains is proposed as a possible cause of the scatter observed in raw laboratory breaker index data. Wave group testing has revealed evolutionary cycles in local energy density during deep water propagation and that the spatial phasing of this evolution with the initiation of shoaling yielded considerably different shoaling and breaking regimes. Critically, smaller waves within the group, particularly those occurring at the front of the wave group were, at times, able to propagate into shallower water before breaking than is presently predicted by existing design guides. Causes for this discrepancy, including differences in definitions of water level and depth are investigated. However, discrepancies between observed and predicted values are found to remain. Revision to present design guidelines to directly incorporate non-linear group effects and group-induced water level variation are presented.

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18

Lee, J. H., J. P. Monty, J. Elsnab, A. Toffoli, A. V. Babanin, and A. Alberello. "Estimation of Kinetic Energy Dissipation from Breaking Waves in the Wave Crest Region." Journal of Physical Oceanography 47, no. 5 (May 2017): 1145–50. http://dx.doi.org/10.1175/jpo-d-16-0273.1.

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AbstractWave-induced turbulence due to breaking in the absence of surface shear stresses is investigated experimentally. A high-fidelity particle image velocimetry (PIV) technique is used to measure the turbulence near the water surface, inside the wave crests. The spatial velocity vector fields of the breaking waves acquired from PIV provide accurate vertical velocity profiles near the air–water interface, as well as wavenumber velocity spectra beneath the breaking waves at different depths. These velocity spectra exhibit a Kolmogorov interval at high wavenumbers, indicating the presence of isotropic turbulence and permitting an estimation of energy dissipation rates. The depth dependence of dissipation rates of the breaking waves generated in the laboratory shows a scaling similar to that found in wind-forced breaking waves in the field. A phase dependence in the dissipation rates of turbulence kinetic energy is also observed, which should be considered to improve the accuracy of the estimated and modeled wave energy dissipation.

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19

HULT, ERIN L., CARY D. TROY, and JEFFREY R. KOSEFF. "The breaking of interfacial waves at a submerged bathymetric ridge." Journal of Fluid Mechanics 637 (September 17, 2009): 45–71. http://dx.doi.org/10.1017/s0022112009008040.

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The breaking of periodic progressive two-layer interfacial waves at a Gaussian ridge is investigated through laboratory experiments. Length scales of the incident wave and topography are used to parameterize when and how breaking occurs. Qualitative observations suggest both shear and convection play a role in the instability of waves breaking at the ridge. Simultaneous particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) measurements are used to calculate high resolution, two-dimensional velocity and density fields from which the local gradient Richardson number Rig is calculated. The transition to breaking occurred when 0.2 ≤ Rig ≤ 0.4. In these wave-ridge breaking events, the destabilizing effects of waves steepening in shallow layers may be responsible for breaking at higher Rig than for similar waves breaking through shear instability in deep water (Troy & Koseff, J. Fluid Mech., vol. 543, 2005b, p. 107). Due to the effects of unsteadiness, nonlinear shoaling and flow separation, the canonical Rig > 0.25 is not sufficient to predict the stability of interfacial waves. A simple model is developed to estimate Rig in waves between finite depth layers using scales of the incident wave scale and topography. The observed breaking transition corresponds with a constant estimated value of Rig from the model, suggesting that interfacial shear plays an important role in initial wave instability. For wave amplitudes above the initial breaking transition, convective breaking events are also observed.

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20

Hsiao, Shih-Chun, Han-Lun Wu, Wei-Bo Chen, Wen-Dar Guo, Chih-Hsin Chang, and Wen-Ray Su. "Effect of Depth-Induced Breaking on Wind Wave Simulations in Shallow Nearshore Waters off Northern Taiwan during the Passage of Two Super Typhoons." Journal of Marine Science and Engineering 9, no. 7 (June 26, 2021): 706. http://dx.doi.org/10.3390/jmse9070706.

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Super Typhoons Maria (2018) and Lekima (2019) were adopted for this case study, although they only passed the northern offshore waters of Taiwan without making landfall. A direct modification technique was employed to create the atmospheric conditions for a wave-circulation model to hindcast large typhoon-driven waves. The radius of the modified scale (Rtrs) for a hybrid typhoon wind plays an important role in the significant wave height (SWH) simulations during the passage of typhoons. The maximum increment in peak SWH reached 3.0 m and 5.0 m in the deep ocean for Super Typhoons Maria (2018) and Lekima (2019), respectively if the Rtrs was increased from 4 × Rmax (radius of the maximum wind) to 7 × Rmax. The SWHs induced by the typhoon winds in the surf zone were more sensitive to different wave-breaking formulations used in the wave-circulation model. The maximum difference in peak SWH reached 2.5 m and 1.2 m for Super Typhoons Maria (2018) and Lekima (2019), respectively, when the wave-breaking formulations of BJ78 (proposed by Battjes and Janssen in 1978) and CT93 (proposed by Church and Thornton in 1993) were introduced to the wave-circulation model. The SWH simulations in the surf zone were insensitive to the wave-breaking criterion (γ) during the passage of typhoons. In shallow nearshore waters, the utilization of a constant γ for the wave-circulation model always produces peak SWHs that are smaller than those using γ based on local steepness or peak steepness.

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21

Simon, Bruno, Christos E. Papoutsellis, Michel Benoit, and Marissa L. Yates. "Comparing methods of modeling depth-induced breaking of irregular waves with a fully nonlinear potential flow approach." Journal of Ocean Engineering and Marine Energy 5, no. 4 (November 2019): 365–83. http://dx.doi.org/10.1007/s40722-019-00154-7.

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22

Rong, Qi, Fangrong Hu, Yuanyuan Li, Shan Yin, Mingzhu Jiang, Tong Li, Dongxia Li, and Yue’e Wang. "Structural symmetry breaking induced polarization sensitivity enhancement: Used for THz tri-band mechanical tunability." Modern Physics Letters B 33, no. 05 (February 20, 2019): 1950032. http://dx.doi.org/10.1142/s0217984919500325.

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A symmetry broken hexagram metamaterial (SBHM) is presented to enhance the polarization sensitivity, and thus realize mechanically controlling the transmissions of tri-band in terahertz (THz) region. This SBHM has different electromagnetic response for rotating clockwise and anticlockwise, respectively. When incident THz wave is polarized in the direction of [Formula: see text], the SBHM has three stopbands with central frequencies at 0.36 THz, 0.52 THz and 0.75 THz, respectively. When the SBHM rotates clockwise [Formula: see text], the transmission of 0.52 THz increases from 0.17 to 0.85, and its modulation depth reaches 68%. On the contrary, when it rotates anticlockwise [Formula: see text], the transmissions of the other two bands can be modulated simultaneously, and their modulation depth are 78% and 40%, respectively. The physical mechanism for the tunability is investigated using finite-integration time-domain (FITD) method. The results indicated that the tri-band tunability in the SBHM is due to the mode transfer and polarization sensitivity enhancement which is induced by near field coupling. This novel design proves a new way for modulation, selection and switching of the THz wave at multiband.

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23

GRUE, JOHN, ATLE JENSEN, PER-OLAV RUSÅS, and J. KRISTIAN SVEEN. "Breaking and broadening of internal solitary waves." Journal of Fluid Mechanics 413 (June 25, 2000): 181–217. http://dx.doi.org/10.1017/s0022112000008648.

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Solitary waves propagating horizontally in a stratified fluid are investigated. The fluid has a shallow layer with linear stratification and a deep layer with constant density. The investigation is both experimental and theoretical. Detailed measurements of the velocities induced by the waves are facilitated by particle tracking velocimetry (PTV) and particle image velocimetry (PIV). Particular attention is paid to the role of wave breaking which is observed in the experiments. Incipient breaking is found to take place for moderately large waves in the form of the generation of vortices in the leading part of the waves. The maximal induced fluid velocity close to the free surface is then about 80% of the wave speed, and the wave amplitude is about half of the depth of the stratified layer. Wave amplitude is defined as the maximal excursion of the stratified layer. The breaking increases in power with increasing wave amplitude. The magnitude of the induced fluid velocity in the large waves is found to be approximately bounded by the wave speed. The breaking introduces a broadening of the waves. In the experiments a maximal amplitude and speed of the waves are obtained. A theoretical fully nonlinear two-layer model is developed in parallel with the experiments. In this model the fluid motion is assumed to be steady in a frame of reference moving with the wave. The Brunt-Väisälä frequency is constant in the layer with linear stratification and zero in the other. A mathematical solution is obtained by means of integral equations. Experiments and theory show good agreement up to breaking. An approximately linear relationship between the wave speed and amplitude is found both in the theory and the experiments and also when wave breaking is observed in the latter. The upper bound of the fluid velocity and the broadening of the waves, observed in the experiments, are not predicted by the theory, however. There was always found to be excursion of the solitary waves into the layer with constant density, irrespective of the ratio between the depths of the layers.

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24

Bastidas, Luis A., James Knighton, and Shaun W. Kline. "Parameter sensitivity and uncertainty analysis for a storm surge and wave model." Natural Hazards and Earth System Sciences 16, no. 10 (September 30, 2016): 2195–210. http://dx.doi.org/10.5194/nhess-16-2195-2016.

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Abstract. Development and simulation of synthetic hurricane tracks is a common methodology used to estimate hurricane hazards in the absence of empirical coastal surge and wave observations. Such methods typically rely on numerical models to translate stochastically generated hurricane wind and pressure forcing into coastal surge and wave estimates. The model output uncertainty associated with selection of appropriate model parameters must therefore be addressed. The computational overburden of probabilistic surge hazard estimates is exacerbated by the high dimensionality of numerical surge and wave models. We present a model parameter sensitivity analysis of the Delft3D model for the simulation of hazards posed by Hurricane Bob (1991) utilizing three theoretical wind distributions (NWS23, modified Rankine, and Holland). The sensitive model parameters (of 11 total considered) include wind drag, the depth-induced breaking γB, and the bottom roughness. Several parameters show no sensitivity (threshold depth, eddy viscosity, wave triad parameters, and depth-induced breaking αB) and can therefore be excluded to reduce the computational overburden of probabilistic surge hazard estimates. The sensitive model parameters also demonstrate a large number of interactions between parameters and a nonlinear model response. While model outputs showed sensitivity to several parameters, the ability of these parameters to act as tuning parameters for calibration is somewhat limited as proper model calibration is strongly reliant on accurate wind and pressure forcing data. A comparison of the model performance with forcings from the different wind models is also presented.

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25

Bastidas, L. A., J. Knighton, and S. W. Kline. "Parameter sensitivity and uncertainty analysis for a storm surge and wave model." Natural Hazards and Earth System Sciences Discussions 3, no. 10 (October 29, 2015): 6491–534. http://dx.doi.org/10.5194/nhessd-3-6491-2015.

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Abstract. Development and simulation of synthetic hurricane tracks is a common methodology used to estimate hurricane hazards in the absence of empirical coastal surge and wave observations. Such methods typically rely on numerical models to translate stochastically generated hurricane wind and pressure forcing into coastal surge and wave estimates. The model output uncertainty associated with selection of appropriate model parameters must therefore be addressed. The computational overburden of probabilistic surge hazard estimates is exacerbated by the high dimensionality of numerical surge and wave models. We present a model parameter sensitivity analysis of the Delft3D model for the simulation of hazards posed by Hurricane Bob (1991) utilizing three theoretical wind distributions (NWS23, modified Rankine, and Holland). The sensitive model parameters (of eleven total considered) include wind drag, the depth-induced breaking γB, and the bottom roughness. Several parameters show no sensitivity (threshold depth, eddy viscosity, wave triad parameters and depth-induced breaking αB) and can therefore be excluded to reduce the computational overburden of probabilistic surge hazard estimates. The sensitive model parameters also demonstrate a large amount of interactions between parameters and a non-linear model response. While model outputs showed sensitivity to several parameters, the ability of these parameters to act as tuning parameters for calibration is somewhat limited as proper model calibration is strongly reliant on accurate wind and pressure forcing data. A comparison of the model performance with forcings from the different wind models is also presented.

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26

Chen, Siyu, Fangli Qiao, Chuanjiang Huang, and Zhenya Song. "Effects of the Non-breaking Surface Wave-induced Vertical Mixing on Winter Mixed Layer Depth in Subtropical Regions." Journal of Geophysical Research: Oceans 123, no. 4 (April 2018): 2934–44. http://dx.doi.org/10.1002/2017jc013038.

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27

Saruwatari, Ayumi, Junichi Otsuka, and Yasunori Watanabe. "SEDIMENT ADVECTION AND DIFFUSION BY OBLIQUELY DESCENDING EDDIES." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 96. http://dx.doi.org/10.9753/icce.v36.sediment.96.

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Three-dimensional vortex structures involving obliquely descending eddies (ODE), produced by depth-induced breaking-waves, has been proved to be associated with local sediment suspension in the surf zone (Zhou et al., 2017); vertical velocity fluctuations around the ODEs induces sediment suspension near the bed. Otsuka et al. (2017) explained the mechanical contributions of the ODEs to enhance local sediment suspension under the breaking waves and modeled the vortex-induced suspension to predict the profile of the equilibrium sediment concentration in the surf zone. In order to predict local behaviors of sediment, however, sediment-turbulence interactions in the transitional turbulence under breaking waves need to be understood. The interaction may be described in terms of Schmidt number (Sc). Sc has been empirically determined for trivial steady flows such as open channel or pipe flows. In the surf zone where organized flows evolve into a turbulent bore, the interaction may vary with the transitional feature of turbulence during a wave-breaking process, and thus Sc may be variable in time and space. No appropriate Sc model has been proposed for the surf zone flow. A parametric study on the sediment motion with respect to the variation of Sc is required for better prediction of sediment transport in the surf zone. In this study, contributions of the sediment advection and diffusion in the vortex structure to the concentration are computationally investigated. Effects of Sc to the sediment suspension and diffusion process will be also discussed in this work.

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28

Dogra, Manish, and Pankaj Jain. "Detection of Concrete Damage Using Ultrasonic Pulse Velocity Method." Journal of Advance Research in Mechanical & Civil Engineering (ISSN: 2208-2379) 3, no. 8 (August 31, 2016): 01–05. http://dx.doi.org/10.53555/nnmce.v3i8.314.

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Ultrasonic Pulse Velocity (UPV) method is used to detect cracks and flaws inside the concrete structure. There are two types of simulated cracks, namely, cracks perpendicular to axis of element and cracks parallel to axis of element were induced without breaking them. The method can be used to measure the depth of vertical cracks. The degree of accuracy is high, if the distance is maintained between 100 - 200 mm. However, for measuring horizontal cracks, this method does not give the result with high degree of accuracy. But within a distance of 100-200 mm between the transducers, the depth of the horizontal cracks can be estimated to a reasonable degree of accuracy. Hence, the distance between the transducers plays an important role degree of accuracy of measuring depth.

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29

Ruessink, B. G. "Observations of Turbulence within a Natural Surf Zone." Journal of Physical Oceanography 40, no. 12 (December 1, 2010): 2696–712. http://dx.doi.org/10.1175/2010jpo4466.1.

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Abstract Here, the Reynolds stresses 〈u′w′〉 and 〈υ′w′〉, where u′, υ′, and w′ are the cross-shore, alongshore, and vertical turbulence velocities, respectively, and the angle brackets represent time averaging, are used to diagnose turbulence dynamics beneath natural breaking surf-zone waves. The data were collected at Truc Vert Beach, France, during a 12-day period in 1–3-m water depth with strong cross-shore and alongshore currents under high-energy wave conditions (offshore significant wave heights ranged between 2 and 8 m). The 〈u′w′〉 term is predominantly negative, increases with the ratio of wave height Hs to water depth h (∼degree of wave breaking), and decreases in magnitude toward the bed. This supports the view that the cross-shore shear stress is due to breaking-induced vortices that transport high-speed cross-shore flow downward and disintegrate close to the bed. The occasional positive sign of 〈u′w′〉 within the lower 15%–20% of the water column indicates that sometimes surface-generated turbulence is overwhelmed by bed-generated turbulence, but the conditions when this happens are not clear from the data. The term 〈υ′w′〉 is persistently of opposite sign to the alongshore mean current and decreases with height above the seabed, implying that 〈υ′w′〉 is due to bottom boundary layer processes rather than surface-generated turbulence. The bottom drag coefficient amounted to 1.6 × 10−3, similar to earlier observations. As in other high-Reynolds-number geophysical flows, time series of u′w′ and υ′w′ comprise intermittently large, short-duration (here, ∼1 s) stress events that in the data contribute considerably to the net stress in only 3%–15% of the time. The data further show that the turbulent kinetic energy is depth uniform and increases with Hs/h. The depth-averaged Froude-scaled turbulent kinetic energy beneath surf-zone bores is 0.025, a factor of 2 to 3 less than observed beneath regular laboratory waves.

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30

KAHLERT, CLAUS. "THE EFFECTS OF SYMMETRY BREAKING IN CHUA'S CIRCUIT AND RELATED PIECEWISE-LINEAR DYNAMICAL SYSTEMS." International Journal of Bifurcation and Chaos 03, no. 04 (August 1993): 963–79. http://dx.doi.org/10.1142/s0218127493000805.

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The behavior of transfer and return maps in the intermediate region of Chua's circuit and related systems undergoes a number of changes as the symmetry of the dynamics is broken, i.e., the separating planes are moved away from symmetric positions. We employ the technique of maps induced by the flow of the system and construct the critical curves for the maps in the intermediate region of state space. The influence of a broken symmetry on the critical curves and the flow is discussed in depth. We demonstrate that any breaking of symmetry potentially weakens and eventually destroys the chaos producing mechanisms.

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31

Van Dongeren, Ap, Andre Van der Westhuysen, Jacco Groeneweg, Gerbrant Van Vledder, Joost Lansen, Alfons Smale, Caroline Gautier, Herman Peters, and Ivo Wenneker. "SPECTRAL WAVE MODELLING IN TIDAL INLET SEAS: RESULTS FROM THE SBW WADDEN SEA PROJECT." Coastal Engineering Proceedings 1, no. 32 (January 29, 2011): 44. http://dx.doi.org/10.9753/icce.v32.waves.44.

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Over the last five years a research program has been carried out to assess the performance of the spectral wave model SWAN in the Wadden Sea so that it may be used for the transformation of offshore wave conditions to wave boundary conditions near the sea defenses (dikes and dunes). The assessment was done on the basis of extensive wave measurements conducted in Ameland inlet and the Dutch Eastern Wadden Sea, as well as relevant data from lakes and estuaries. After a first round of assessment, we found that SWAN performed reasonably well for storm conditions but three aspects required further attention. Firstly, focusing on the main channel, SWAN formulations needed to be modified in order to eliminate overprediction of the significant wave height in opposing currents. Secondly, the primary spectral peak of North Sea waves penetrating into the inlet was underpredicted. Best results were obtained when the refraction of low-frequency waves was limited and the bottom friction coefficient was set at a lower value than the current default for wind seas. Thirdly, over the tidal flats the computed ratio of integral wave height over water depth showed an apparent upper limit using the conventional Battjes and Janssen (1978) depth-limited wave breaking formulation, because the wave growth over finite depth is hampered by the present formulation of depth-induced wave breaking. The problem has been solved using a new breaker formulation. All these improvements have lead to a wave transformation model with which reliable wave conditions in the Wadden Sea and related complex areas can be determined.

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32

LI, LI, and ROBERT A. DALRYMPLE. "Instabilities of the undertow." Journal of Fluid Mechanics 369 (August 25, 1998): 175–90. http://dx.doi.org/10.1017/s0022112098001694.

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The steady undertow created by waves breaking at a beach and slowly flowing offshore can become unstable and create a train of submerged offshore migrating vortices with shorter length scales and longer time scales than the incident waves, as shown by Matsunaga, Takehara & Awaya (1988, 1994). These vortices rotate about horizontal axes parallel to the shoreline. Our larger-scale laboratory experiments show that an additional layer of vortices can exist over the water depth, with vortices near the water surface rotating in the same direction as the wave-induced water particle trajectories, while those located at about mid-depth rotate in the opposite direction.A theoretical and numerical analysis shows that these vortices are due to instabilities of the undertow. Far offshore of the surf zone, the vortex trains decay because the velocity profile for the undertow becomes linear over depth, hence neutrally stable to any disturbances.

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33

Li, Zhuoran, Akash Venkateshwaran, and Shooka Karimpour. "Turbulent Characteristics and Air Entrainment Patterns in Breaking Surge Waves." Fluids 6, no. 12 (November 23, 2021): 422. http://dx.doi.org/10.3390/fluids6120422.

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Breaking surge waves are highly turbulent three-dimensional (3D) flows, which occur when the water flow encounters a sudden change in depth or velocity. The 3D turbulent structures across a breaking surge are induced by the velocity gradient across the surge and phase discontinuity at the front. This paper examined the turbulent structures in breaking surge waves with Froude numbers of 1.71 and 2.13 by investigating the air entrainment and perturbation patterns across the surge front. A combination of the Volume Of Fluid (VOF) method and Large Eddy Simulation (LES) was utilized to capture air entrainment and turbulent structures simultaneously. The 3D nature of the vortical structures was simulated by implementing a spanwise periodic boundary. The water surface perturbation and air concentration profiles were extracted, and the averaged air concentration profiles obtained from the numerical simulations were consistent with laboratory observations reported in the literature. The linkage between turbulent kinetic energy distribution and air entrainment was also explored in this paper. Finally, using quadrant analysis and the Q-criterion, this paper examined the role of the spanwise perturbations in the development of turbulent structures in the surge front.

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34

Man, Lin Tao, and Shou Ju Li. "Numerical Simulation of Rock Fragmentation Process Induced by Two Disc Cutters." Advanced Materials Research 366 (October 2011): 224–28. http://dx.doi.org/10.4028/www.scientific.net/amr.366.224.

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Rock fragmentation processes induced by two cutters were simulated by ABAQUS software with different cutter spacing. A series of numerical experiments reproduce the progressive process of rock fragmentation in indentation. The influence of different cutter spacing on the penetration process can also be clearly researched. Rock fragmentation process induced by two TBM disc cutters was performed using the finite element method. The simulation not only provided a realistic description of the rock fragmentation mechanism, but also supported the sufficient proof for the cutter spacing optimization between adjacent disc cutters for a given penetration depth. When the penetration is 6 mm, the cutter spacing optimization is 48 mm. The result shows that the numerical simulations will contribute to an improved knowledge of rock fragmentation in indentation and will be useful for performance assessment of TBM, which will enhance the efficiency of rock breaking.

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35

Wu, Yun-Ta, Philip Li-Fan Liu, Philip Li-Fan Liu, Kao-Shu Hwang, Kao-Shu Hwang, Hwung-Hweng Hwung, and Hwung-Hweng Hwung. "A UNIFIED RUNUP FORMULA FOR BREAKING SOLITARY WAVES ON A UNIFORM BEACH." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 3. http://dx.doi.org/10.9753/icce.v36.currents.3.

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For coastal management, it is of great importance to understand long-wave induced runup processes and predict maximum runup heights. Long-wave in nature could take different forms, such as swells, storm surges and tsunamis. One of the fundamental waveforms is solitary wave, which has a permanent form in a constant depth. Thus, the issue of solitary wave propagation, shoaling, breaking and runup has been an active research area in coastal engineering community, using experimental, numerical and analytical approaches. Among existing runup experiments, only limited numbers of experiments were conducted in large-scale wave flume facilities because of the lack of easy access. To enhance the range of surf parameters for breaking solitary waves, new laboratory experiments were carried out in a large-scale wave flume with a 1/100 slope. Several wave conditions in the experiments were on the borderline of plunging and spilling breakers. The main objective of this paper is twofold. The first aim is to present a new dataset for solitary wave runup. The second objective aims to develop a unified empirical formula, based on the available runup data in the literature and the present new data, for the runup of breaking solitary waves on a uniform slope.

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36

Liao, Ying-Po, and James M. Kaihatu. "Numerical Investigation of Wind Waves in the Persian Gulf: Bathymetry Effects." Journal of Atmospheric and Oceanic Technology 33, no. 1 (January 2016): 17–31. http://dx.doi.org/10.1175/jtech-d-15-0066.1.

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AbstractThe effects of bathymetry on the process of wind-wave generation in the Persian Gulf have been investigated using a long-term hindcasting analysis. A 5-yr (2004–08) hindcasting procedure is first performed (denoted as origin) by using the Simulating Waves Nearshore (SWAN) model and COAMPS wind field data. Two alternative scenarios, in which wave breaking (noBrek) and depth-induced refraction (noRefc) are deactivated, are also generated. By comparing the results from alternative cases with those from the ordinary cases, a 5-yr total energy deviation (TED) is calculated and presented as seasonal contour maps depicting the sensitivity to bathymetry. The results show only ±2% TED found in noBrek, but up to ±20% TED found in noRefc, an order of magnitude larger than depth-induced breaking. Similarly, the seasonal effects of refraction on the nearshore wave-propagating directions can be investigated by comparison between origin and noRefc. The seasonal histograms of mean wave angle are plotted and discussed for three selected nearshore sites around Qatar, located at the western, northern, and eastern sides of the peninsula. The largest relative occurrence percentage and the largest peak shift ranging in 10°–20° can be found at the northern side, while the eastern side results in a weaker and more random distribution in the winter (the strong shamal season) due to the leeside location. The effect of fetch-limited wind-wave generation is also present at the eastern site, as remotely generated waves propagating eastward over a long fetch toward this site offset southward-propagating waves generated by dominant winds from the north over a limited fetch.

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37

Matsunaga, Nobuhiro, Kosei Takehara, and Yoichi Awaya. "COHERENT EDDIES INDUCED BY BREAKERS ON A SLOPING FIELD." Coastal Engineering Proceedings 1, no. 21 (January 29, 1988): 15. http://dx.doi.org/10.9753/icce.v21.15.

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The separation of boundary layer occurs periodically near a breaking point when incident waves climbing up a sloping bed are about to break. Not the breaker but the separation forms an unsteady coherent eddy, which suspends a large amount of bed material. A row of steady vortices has been found along the water surface of an offshore zone. Its formation is due to the shear instability between shoreward steady flow induced near the bed and offshore steady flow near the water surface. Moving in the offshore direction, the steady vortices repeat amalgamation each other and increase their intervals at the order of mean water depth. They decay after reaching to the region where the shear rate is not enough between the two steady flows. This shear instability may be excited by the periodic separation of boundary 1aye r.

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38

Caires, Sofia, and Marcel R. A. Van Gent. "WAVE HEIGHT DISTRIBUTION IN CONSTANT AND FINITE DEPTHS." Coastal Engineering Proceedings 1, no. 33 (October 15, 2012): 15. http://dx.doi.org/10.9753/icce.v33.waves.15.

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Several alternatives to the Rayleigh distribution have been proposed for describing individual wave heights in regions where depth-induced wave breaking occurs. The most widely used of these is the so-called Battjes and Groenendijk distribution. This distribution has been derived and validated in a context of a shallow water foreshore waves propagating over a gently sloping shallow region towards the shore. Its validity for waves propagating in regions with shallow flat bottoms is investigated here. It is concluded that the distribution on average underestimates (outside its range of validity) high wave height measurements in shallow flat bottoms by as much as 15%.

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39

Pourzangbar, Ali, Miguel A. Losada, Aniseh Saber, Lida Rasoul Ahari, Philippe Larroudé, Mostafa Vaezi, and Maurizio Brocchini. "Prediction of non-breaking wave induced scour depth at the trunk section of breakwaters using Genetic Programming and Artificial Neural Networks." Coastal Engineering 121 (March 2017): 107–18. http://dx.doi.org/10.1016/j.coastaleng.2016.12.008.

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40

Sous, Damien. "A Numerical Assessment of Artificial Reef Pass Wave-Induced Currents as a Renewable Energy Source." Journal of Marine Science and Engineering 7, no. 9 (August 22, 2019): 284. http://dx.doi.org/10.3390/jmse7090284.

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The present study aims to estimate the potential of artificial reef pass as a renewable source of energy. The overall idea is to mimic the functioning of natural reef–lagoon systems in which the cross-reef pressure gradient induced by wave breaking is able to drive an outward flow through the pass. The objective is to estimate the feasibility of a positive energy breakwater, combining the usual wave-sheltering function of immersed breakwater together with the production of renewable energy by turbines. A series of numerical simulations is performed using a depth-averaged model to understand the effects of each geometrical reef parameter on the reef–lagoon hydrodynamics. A synthetic wave and tide climate is then imposed to estimate the potential power production. An annual production between 50 and 70 MWh is estimated.

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41

Lee, Han Soo, Takao Yamashita, Tomoaki Komaguchi, and Toyoaki Mishima. "STORM SURGE IN SETO INLAND SEA WITH CONSIDERATION OF THE IMPACTS OF WAVE BREAKING ON SURFACE CURRENTS." Coastal Engineering Proceedings 1, no. 32 (January 29, 2011): 17. http://dx.doi.org/10.9753/icce.v32.currents.17.

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Storm surge and storm wave simulations in Seto Inland Sea (SIS) in Japan were conducted for Typhoon Yancy (9313) and Chaba (0416) using an atmosphere (MM5)-wave (SWAN)-ocean (POM) modeling system. In the coupled modeling system, a new method for wave-current interaction in terms of momentum transfer due to whitecapping in deep water and depth-induced wave breaking in shallow water was considered. The calculated meteorological and wave fields show good agreement with the observations in SIS and its vicinities. The storm surge results also exhibit good accordance with the observations in SIS. To resolve a number of islands in SIS, we also performed numerical experiments with different grid resolutions and obtained improved results from higher resolutions in wave and ocean circulation fields.

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42

Komijani, Homayoon, and Jaak Monbaliu. "The wave-current interaction in the coastal area." Journal of Marine Research 77, no. 5 (September 1, 2019): 375–405. http://dx.doi.org/10.1357/002224019833406169.

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In our investigation of the effect of wind-waves on barotropic mean flow in coastal areas, we compare two methods for calculating wave-induced force. The wave field is simulated by the nearshore spectral wave model SWAN. The wave-induced force (calculated using the radiation stress gradient and dissipation methods) and the Stokes drift are integrated in the COHERENS circulation model in the depth-averaged mode. The coupled set is validated using well-known academic test cases of planar beach and single-barred beach. Finally, in a two-dimensional test case based on Belgian coastal waters we compare simulations of mean flow using the two methods of calculating waveinduced force against field data.<br/> We show clearly that the two methods for calculation of wave-induced force yield very different results even in depth-averaged mode, depending on the angle of incident wave. Simulation of waveinduced circulation using the wave dissipation approach gives better results than using the radiation stress gradient approach. This is clearly visible for strong wave conditions in which the wind is blowing almost parallel to the shore. Under these conditions, the white-capping type of wave breaking is the dominant dissipation mechanism; in the radiation stress gradient, the dissipation signal is not visible, because the energy loss in the spectrum is compensated by wind input.

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43

Donelan, Mark A., Alexander V. Babanin, Ian R. Young, Michael L. Banner, and Cyril McCormick. "Wave-Follower Field Measurements of the Wind-Input Spectral Function. Part I: Measurements and Calibrations." Journal of Atmospheric and Oceanic Technology 22, no. 7 (July 1, 2005): 799–813. http://dx.doi.org/10.1175/jtech1725.1.

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Abstract An experimental study of wind energy and momentum input into finite-depth wind waves was undertaken at Lake George, New South Wales, Australia. To measure microscale oscillations of induced pressure above surface waves, a high-precision wave-follower system was developed at the University of Miami, Florida. The principal sensing hardware included Elliott pressure probes, hot-film anemometers, and Pitot tubes. The wave-follower recordings were supplemented by a complete set of relevant measurements in the atmospheric boundary layer, on the surface, and in the water body. This paper is dedicated to technical aspects of the measurement procedure and data analysis. The precision of the feedback wave-following mechanism did not impose any restrictions on the measurement accuracy in the range of wave heights and frequencies relevant to the problem. Thorough calibrations of the pressure transducers and moving Elliott probes were conducted. It is shown that the response of the air column in the connecting tubes provides a frequency-dependent phase shift, which must be accounted for to recover the low-level induced pressure signal. In the finite-depth environment of Lake George, breaking waves play an important role in the momentum exchange between wind and waves, as will be shown in a subsequent paper.

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44

Alewell, C., R. Giesler, J. Klaminder, J. Leifeld, and M. Rollog. "Stable carbon isotopes as indicators for environmental change in palsa peats." Biogeosciences 8, no. 7 (July 8, 2011): 1769–78. http://dx.doi.org/10.5194/bg-8-1769-2011.

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Abstract. Palsa peats are unique northern ecosystems formed under an arctic climate and characterized by a high biodiversity and sensitive ecology. The stability of the palsas are seriously threatened by climate warming which will change the permafrost dynamic and induce a degradation of the mires. We used stable carbon isotope depth profiles in two palsa mires of Northern Sweden to track environmental change during the formation of the mires. Soils dominated by aerobic degradation can be expected to have a clear increase of carbon isotopes (δ13C) with depth, due to preferential release of 12C during aerobic mineralization. In soils with suppressed degradation due to anoxic conditions, stable carbon isotope depth profiles are either more or less uniform indicating no or very low degradation or depth profiles turn to lighter values due to an enrichment of recalcitrant organic substances during anaerobic mineralisation which are depleted in 13C. The isotope depth profile of the peat in the water saturated depressions (hollows) at the yet undisturbed mire Storflaket indicated very low to no degradation but increased rates of anaerobic degradation at the Stordalen site. The latter might be induced by degradation of the permafrost cores in the uplifted areas (hummocks) and subsequent breaking and submerging of the hummock peat into the hollows due to climate warming. Carbon isotope depth profiles of hummocks indicated a turn from aerobic mineralisation to anaerobic degradation at a peat depth between 4 and 25 cm. The age of these turning points was 14C dated between 150 and 670 yr and could thus not be caused by anthropogenically induced climate change. We found the uplifting of the hummocks due to permafrost heave the most likely explanation for our findings. We thus concluded that differences in carbon isotope profiles of the hollows might point to the disturbance of the mires due to climate warming or due to differences in hydrology. The characteristic profiles of the hummocks are indicators for micro-geomorphic change during permafrost up heaving.

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45

Lan, Yuan-Jyh, Tai-Wen Hsu, Rafał Ostrowski, and Marek Szmytkiewicz. "Wave Transformation in a Multi-Bar Surf Zone: Case Study of Lubiatowo (Poland)." Archives of Hydro-Engineering and Environmental Mechanics 63, no. 1 (June 1, 2016): 19–34. http://dx.doi.org/10.1515/heem-2016-0002.

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Abstract The paper presents results of field and theoretical investigations of wave transformation in the surf zone near the IBW PAN Coastal Research Station in Lubiatowo (Poland, the south Baltic Sea). The study site displays multi-bar cross-shore profiles that intensively dissipate wave energy, mostly induced by breaking. The main field data comprise wave heights and cross-shore bathymetric profiles.Wave transformation is modelled theoretically by two approaches, namely the IBW PAN phase-averaged wave transformation model and the approach based on the hydraulic jump model, developed by Hsu & Lai (2009) for hydrological situations encountered under the actual conditions of two field campaigns - in 1987 and 1996. Discrepancies between the measured data and the model results are discussed. In general, the model results are in good agreement with the in-situ observations. The comparison of the field data with the computational results concerns a part of the surf zone between about 5 m water depth and the first nearshore stable bar, where the depth amounts to ca. 1.2 m.

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46

Lu, Senxun, Haijiang Liu, and Xiaohu Deng. "An Experimental Study of the Run-Up Process of Breaking Bores Generated by Dam-Break Under Dry- and Wet-Bed Conditions." Journal of Earthquake and Tsunami 12, no. 02 (June 2018): 1840005. http://dx.doi.org/10.1142/s1793431118400055.

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In this study, a series of dam-break laboratory experiments were carried out to investigate the run-up process of breaking bores under dry- and wet-bed conditions. Detailed measurements were conducted to reveal differences in the run-up hydrodynamic characteristics under these two conditions, e.g. the bore front profile, the maximum run-up height and duration, and the instantaneous bore front velocity. Two successive bores were observed under the wet-bed run-up process, while multiple bores (three bores in general) were generated during the dry-bed run-up process due to the significant bottom friction effect. A linear relationship with the uniform gradient is found between the maximum run-up height and the initial water head for both dry- and wet-bed conditions, indicating that difference in the maximum run-up height between the dry- and specified wet-bed cases or among various wet-bed cases is not sensitive to the initial water head. Under the same initial water head, although the dry-bed run-up process takes a longer duration than that of wet-bed cases, the maximum run-up height is smallest for the dry-bed case and gradually increases with the increase of the initial downstream water depth for wet-bed cases. Under the wet-bed conditions, temporal variation of the bore front run-up velocity can be classified into two stages, i.e. the acceleration stage induced by the relatively large incident bore front water depth (large onshore hydrostatic pressure gradient) and the deceleration stage governed by the offshore-directed gravity force and bottom friction. Nevertheless, due to the small incident bore front water depth, run-up process under the dry-bed conditions does not show the acceleration stage.

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47

Sokolov, Andrei, and Boris Chubarenko. "Wind Influence on the Formation of Nearshore Currents in the Southern Baltic: Numerical Modelling Results." Archives of Hydro-Engineering and Environmental Mechanics 59, no. 1-2 (October 1, 2012): 37–48. http://dx.doi.org/10.2478/v10203-012-0003-3.

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Abstract A two-dimensional numerical model was used for a simulation of vertical average longshore currents generated by both wind friction and wind-wave action in the nearshore zone. The modelling domain includes the southern part of the Baltic Proper (all boundaries were closed). Wind, uniform in space and varying in time, was the only forcing in the model. The correlation coefficient higher than 0.8 was obtained by model calibration versus the field measurements of currents conducted at the Lubiatowo field station (southern Baltic) during about 1.5 months in 2006. Comparative simulations of total currents including both wind-induced drift and wave components, and of total currents including only a wind-induced drift component, showed that the input of the drift component into currents in the nearshore zone is greater than commonly believed.Wind-induced drift strongly dominates outside the zone of wave transformation, and its input into the total resulting currents remains noticeable even in a zone between the shoreline and the depth of the first wave breaking. Thus, wind-induced drift constitutes up to 50% of the resulting longshore currents for longshore winds and no less than 20% of the longshore component of currents for winds at 45 degrees to the longshore direction.

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48

Zhou, Bowen, and Fotini Katopodes Chow. "Nested Large-Eddy Simulations of the Intermittently Turbulent Stable Atmospheric Boundary Layer over Real Terrain." Journal of the Atmospheric Sciences 71, no. 3 (February 27, 2014): 1021–39. http://dx.doi.org/10.1175/jas-d-13-0168.1.

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Abstract The nighttime stable atmospheric boundary layer over real terrain is modeled with nested high-resolution large-eddy simulations (LESs). The field site is located near Leon, Kansas, where the 1999 Cooperative Atmosphere–Surface Exchange Study took place. The terrain is mostly flat with an average slope of 0.5°. The main topographic feature is a shallow valley oriented in the east–west direction. The night of 5 October is selected to study intermittent turbulence under prevailing quiescent conditions. Brief turbulent periods triggered by shear-instability waves are modeled with good magnitude and temporal precision with a dynamic reconstruction turbulence closure. In comparison, conventional closures fail to excite turbulent motions and predict a false laminar flow. A plausible new intermittency mechanism, previously unknown owing to limited spatial coverage of field instruments at this site, is unveiled with the LESs. Turbulence can be generated through gravity wave breaking over a stagnant cold-air bubble in the valley upwind of the main tower. The bubble is preceded by the formation of a valley cold-air pool due to down-valley drainage flows during the evening transition. The bubble grows in depth by entraining cold down-valley and downslope flows from below and is eroded by shear-induced wave breaking on the top. The cyclic process of formation and erosion is repeated during the night, leading to sporadic turbulent bursting.

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Pollmann, Friederike, Jonas Nycander, Carsten Eden, and Dirk Olbers. "Resolving the horizontal direction of internal tide generation." Journal of Fluid Mechanics 864 (February 7, 2019): 381–407. http://dx.doi.org/10.1017/jfm.2019.9.

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The mixing induced by breaking internal gravity waves is an important contributor to the ocean’s energy budget, shaping, inter alia, nutrient supply, water mass transformation and the large-scale overturning circulation. Much of the energy input into the internal wave field is supplied by the conversion of barotropic tides at rough bottom topography, which hence needs to be described realistically in internal gravity wave models and mixing parametrisations based thereon. A new semi-analytical method to describe this internal wave forcing, calculating not only the total conversion but also the direction of this energy flux, is presented. It is based on linear theory for variable stratification and finite depth, that is, it computes the energy flux into the different vertical modes for two-dimensional, subcritical, small-amplitude topography and small tidal excursion. A practical advantage over earlier semi-analytical approaches is that the new one gives a positive definite conversion field. Sensitivity studies using both idealised and realistic topography allow the identification of suitable numerical parameter settings and corroborate the accuracy of the method. This motivates the application to the global ocean in order to better account for the geographical distribution of diapycnal mixing induced by low-mode internal gravity waves, which can propagate over large distances before breaking. The first results highlight the significant differences of energy flux magnitudes with direction, confirming the relevance of this more detailed approach for energetically consistent mixing parametrisations in ocean models. The method used here should be applicable to any physical system that is described by the standard wave equation with a very wide field of sources.

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Wu, Weiming, Alejandro Sanchez, and Mingliang Zhang. "AN IMPLICIT 2-D DEPTH-AVERAGED FINITE-VOLUME MODEL OF FLOW AND SEDIMENT TRANSPORT IN COASTAL WATERS." Coastal Engineering Proceedings 1, no. 32 (February 2, 2011): 23. http://dx.doi.org/10.9753/icce.v32.sediment.23.

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An implicit depth-averaged 2-D finite volume model has been developed to simulate sediment transport and bed morphological changes under actions of currents and waves near coastal inlets. The model computes the depth-averaged 2-D shallow water flow and non-equilibrium transport of total-load sediment, accounting for the effects of wave radiation stresses and turbulent diffusion induced by currents, waves and wave breaking. The model uses a quadtree rectangular mesh to locally refine the mesh around structures of interest or where the topography and/or flow properties change rapidly. The grid nodes are numbered by means of an unstructured index system for more flexibility of mesh generation. The SIMPLEC algorithm is used to handle the coupling of water level and velocity and the Rhie and Chow’s (1983) momentum interpolation method is adopted to determine the intercell fluxes on non-staggered grid. Well-developed longshore current and wave setup determined with the reduced 1-D momentum equations are used as the cross-shore boundary conditions. The model has been tested in several laboratory and field cases, showing good performance. In particular, it can use a long time step and is efficient in computation on a PC platform. It has a potential for simulation of long-term coastal morphodynamic processes.

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