scholarly journals TIME-VARYING WAVE EFFECTS ON FLOWS AND DYNAMICS AT AN UNSTRATIFIED INLET

2018 ◽  
pp. 45
Author(s):  
Anna Wargula ◽  
Britt Raubenheimer ◽  
Steve Elgar ◽  
Jia-Lin Chen ◽  
Fengyan Shi
Keyword(s):  
Numerical Simulations ◽  
Water Levels ◽  
Wave Radiation ◽  
Field Observations ◽  
Pressure Gradients ◽  
Radiation Stress ◽  
Wave Forcing ◽  
Wave Effects ◽  
Asymmetric Flows ◽  
Coastal Inlets

Surface gravity waves alter discharge and circulation near and within coastal inlets, affecting the exchange and transport of water masses, nutrients, sediments, and pollutants between inland waters and the ocean. Field observations and numerical simulations suggest that, during storms, wave forcing (radiation-stress gradients) owing to wave dissipation across the ebb shoal can enhance fluxes into the inlet (Bertin et al. 2009; Wargula et al. 2014). As a result, water levels may increase inside the bay (Olabarrieta et al. 2011; Dodet et al. 2013), creating an offshore-directed pressure gradient that may balance onshore fluxes during energetic waves, and may enhance offshore fluxes after the waves decrease. Spatial and tidal variability in water depths on the ebb shoal lead to complex wave breaking patterns that drive spatially and tidally asymmetric flows. Here, field observations and numerical simulations are used to evaluate the effects of waves on discharge and circulation, and the relative importance of wave radiation-stress and pressure gradients at an unstratified inlet during and following energetic waves.

scholarly journals Dynamics of Wave Setup over a Steeply Sloping Fringing Reef

2015 ◽  
Vol 45 (12) ◽  
pp. 3005-3023 ◽  
Author(s):  
Mark L. Buckley ◽  
Ryan J. Lowe ◽  
Jeff E. Hansen ◽  
Ap R. Van Dongeren
Keyword(s):  
Wave Theory ◽  
Water Levels ◽  
Wave Radiation ◽  
Linear Wave ◽  
Radiation Stress ◽  
Wave Setup ◽  
Fringing Reef ◽  
Linear Wave Theory ◽  
Stress Gradients ◽  
Wide Range

AbstractHigh-resolution observations from a 55-m-long wave flume were used to investigate the dynamics of wave setup over a steeply sloping reef profile with a bathymetry representative of many fringing coral reefs. The 16 runs incorporating a wide range of offshore wave conditions and still water levels were conducted using a 1:36 scaled fringing reef, with a 1:5 slope reef leading to a wide and shallow reef flat. Wave setdown and setup observations measured at 17 locations across the fringing reef were compared with a theoretical balance between the local cross-shore pressure and wave radiation stress gradients. This study found that when radiation stress gradients were calculated from observations of the radiation stress derived from linear wave theory, both wave setdown and setup were underpredicted for the majority of wave and water level conditions tested. These underpredictions were most pronounced for cases with larger wave heights and lower still water levels (i.e., cases with the greatest setdown and setup). Inaccuracies in the predicted setdown and setup were improved by including a wave-roller model, which provides a correction to the kinetic energy predicted by linear wave theory for breaking waves and produces a spatial delay in the wave forcing that was consistent with the observations.

scholarly journals Reply to “Comments on ‘A Wave-Resolving Simulation of Langmuir Circulations with a Nonhydrostatic Free-Surface Model: Comparison with Craik–Leibovich Theory and an Alternative Eulerian View of the Driving Mechanism’”

2019 ◽  
Vol 49 (3) ◽  
pp. 889-892 ◽  
Author(s):  
Yasushi Fujiwara ◽  
Yutaka Yoshikawa ◽  
Yoshimasa Matsumura
Keyword(s):  
Model Comparison ◽  
Three Dimensional ◽  
Momentum Equation ◽  
Surface Model ◽  
Driving Mechanism ◽  
Radiation Stress ◽  
Wave Effect ◽  
Wave Effects ◽  
Langmuir Circulations ◽  
Free Surface Model

AbstractFujiwara et al. explicitly simulated Langmuir circulations using a wave-resolving simulation (WRS) technique and found that the residual wave effect on vorticity was well represented by the vortex force of the Craik–Leibovich (CL) equation, at least in the simulated situation. In response to the simulation results, Mellor has proposed a view that ubiquitous applicability of the CL formulation is still questionable and that the three-dimensional radiation stress (3DRS) formulation that he has derived encompasses both of the vortex force effect and an effect that is lower order in terms of wave steepness. Here, these opinions are discussed in terms of the approximations used in the wave-averaged formulations. The asymptotic expansion of the Eulerian-averaged momentum equation allows the separate discussion of two different wave effects: pressure correction and torque. It is argued that the approximation adopted in Mellor’s 3DRS formulation is presumably not accurate enough to properly parameterize the wave torque effect, and possible approaches to examine its performance are proposed. We agree with the view that the applicability of the CL formulation needs further investigation. WRS will be a helpful tool for this purpose.

scholarly journals Effects of Wave–Current Interactions on Suspended-Sediment Dynamics during Strong Wave Events in Jiaozhou Bay, Qingdao, China

2018 ◽  
Vol 48 (5) ◽  
pp. 1053-1078 ◽  
Author(s):  
Guan Dong Gao ◽  
Xiao Hua Wang ◽  
Dehai Song ◽  
Xianwen Bao ◽  
Bao Shu Yin ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Wave Energy ◽  
Jiaozhou Bay ◽  
Sediment Dynamics ◽  
Wave Radiation ◽  
Radiation Stress ◽  
Bottom Stress ◽  
Strong Wave ◽  
Wave Radiation Stress ◽  
Mean Current

AbstractWave–current interactions are crucial to suspended-sediment dynamics, but the roles of the associated physical mechanisms, the depth-dependent wave radiation stress, Stokes drift velocity, vertical transfer of wave-generated pressure transfer to the mean momentum equation (form drag), wave dissipation as a source term in the turbulence kinetic energy equation, and mean current advection and refraction of wave energy, have not yet been fully understood. Therefore, in this study, a computationally fast wave model developed by Mellor et al., a Finite Volume Coastal Ocean Model (FVCOM) hydrodynamics model, and the sediment model developed by the University of New South Wales are two-way coupled to study the effect of each wave–current interaction mechanism on suspended-sediment dynamics near shore during strong wave events in a tidally dominated and semiclosed bay, Jiaozhou Bay, as a case study. Comparison of Geostationary Ocean Color Imager data and model results demonstrates that the inclusion of just the combined wave–current bottom stress in the model, as done in most previous studies, is clearly far from adequate to model accurately the suspended-sediment dynamics. The effect of each mechanism in the wave–current coupled processes is also investigated separately through numerical simulations. It is found that, even though the combined wave–current bottom stress has the largest effect, the combined effect of the other wave–current interactions, mean current advection and refraction of wave energy, wave radiation stress, and form drag (from largest to smallest effect), are comparable. These mechanisms can cause significant variation in the current velocities, vertical mixing, and even the bottom stress, and should obviously be paid more attention when modeling suspended-sediment dynamics during strong wave events.

Numerical Study on Coastal Wave and Near-Shore Current Interaction

2014 ◽  
Author(s):  
Jun Tang ◽  
Yongming Shen ◽  
Yigang Lv
Keyword(s):  
Wave Propagation ◽  
Numerical Model ◽  
Water Wave ◽  
Wave Radiation ◽  
Radiation Stress ◽  
Propagation Angle ◽  
Mild Slope Equation ◽  
Near Shore ◽  
Wave Induced ◽  
Wave Radiation Stress

Coastal waves and near-shore currents have been investigated by many researchers. This paper developed a two-dimensional numerical model of near-shore waves and currents to study breaking wave induced current. In the model, near-shore water wave was simulated by a parabolic mild slope equation incorporating current effect and wave energy dissipation due to breaking, and current was simulated by a nonlinear shallow water equation incorporating wave exerted radiation stress. Wave radiation stress was calculated based on complex wave amplitude in the parabolic mild slope equation, and this result in an effective method for calculating wave radiation stress using an intrinsic wave propagation angle that differs from the ones of using explicit wave propagation angle. Wave and current interactions were considered by cycling the wave and current equation to a steady state. The model was used to study waves and wave-induced longshore currents at the Obaköy coastal water which is located at the Mediterranean coast of Turkey. The numerical results for water wave induced longshore current were validated by measured data to demonstrate the efficiency of the numerical model, and water waves and longshore currents were analyzed based on the numerical results.

The Storegga Slide tsunami—comparing field observations with numerical simulations

2005 ◽  
Vol 22 (1-2) ◽  
pp. 195-208 ◽  
Author(s):  
Stein Bondevik ◽  
Finn Løvholt ◽  
Carl Harbitz ◽  
Jan Mangerud ◽  
Alastair Dawson ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Field Observations ◽  
Storegga Slide

scholarly journals Identifying runoff processes on the plot and catchment scale

2006 ◽  
Vol 3 (4) ◽  
pp. 2063-2100 ◽  
Author(s):  
P. Schmocker-Fackel ◽  
F. Naef ◽  
S. Scherrer
Keyword(s):  
Water Retention ◽  
Water Levels ◽  
Water Retention Capacity ◽  
Soil Profiles ◽  
Field Observations ◽  
Rainfall Runoff ◽  
Catchment Scale ◽  
Retention Capacity ◽  
Simplified Method ◽  
Infiltration Parameters

Abstract. Rainfall-runoff models that adequately represent the real hydrological processes and that do not have to be calibrated, are needed in hydrology. Such a model would require information about the runoff processes occurring in a catchment and their spatial distribution. Therefore, the aim of this article is (1) to develop a methodology that allows the delineation of dominant runoff processes (DRP) in the field and with a GIS, and (2) to illustrate how such a map can be used in rainfall-runoff modelling. Soil properties were assessed of 44 soil profiles in two Swiss catchments. On some profiles, sprinkling experiments were performed and soil-water levels measured. With these data, the dominant runoff processes (DRP) were determined using the Scherrer and Naef (2003) process decision scheme. At the same time, a simplified method was developed to make it possible to determine the DRP only on the basis of maps of the soil, topography and geology. In 67% of the soil profiles, the two methods indicated the same processes; in 24% with minor deviations. By transforming the simplified method into a set of rules that could be introduced into a GIS, the distributions of the different DRPs in two catchments could be delineated automatically so that maps of the dominant runoff processes could be produced. These maps agreed well with manually derived maps and field observations. Flood-runoff volumes could be quite accurately predicted on the basis of the rainfall measured and information on the water retention capacity contained in the DRP map. This illustrates the potential of the DRP maps for defining the infiltration parameters used in rainfall-runoff models.

scholarly journals DETERMINATION OF THE WAVE ATTACK ANTICIPATED UPON A STRUCTURE FROM LABORATORY AND FIELD OBSERVATIONS

2011 ◽  
Vol 1 (7) ◽  
pp. 37
Author(s):  
W.A. Venis
Keyword(s):  
Comparative Study ◽  
Model Tests ◽  
Water Levels ◽  
Field Observations ◽  
Wave Impact ◽  
Spring System ◽  
Mass Spring ◽  
The Comparative Study ◽  
The Impact

Model tests have been carried out to obtain an insight into the magnitude of the wave-pressures in various situations. These tests showed, that sharp high pressure peaks occur in addition to the pressures caused by the reflecting of the waves, which pressures are quasi-static. As the structure can be compared with a multiple mass-spring system these pressure-peaks may cause the whole construction to vibrate. Wave-attack therefore can be expressed in terms of impact. Moreover, calculations revealed that the impact pressures were critical factors in determining the strength of the structure. So many model tests were carried out to determine the design and location of the sluices. These tests involved numerous water-levels discharges and waves. Regarding the pressure-peaks a comparative study was made in the model, which led to the structure being designed in such a way that the occurrence of critical impacts was reduced to an acceptable minimum. As it was impossible to avoid the occurrence of impact pressures entirely it remained necessary to determine a basic load for the structure that takes care of the impact pressures. As it has not yet appeared possible physically to determine a theoretical maximum for the impact pressures, it has to be borne in mind that there is a probability that each pressure measured will be exceeded. So this paper describes, how the cumulative frequency curve of the impacts for the case mentioned in 1.1 sub a, which served as a basis for determining the basic load was arrived at by a certain combination of laboratory and field observations. The data used for this purpose were a. Results of wave-impact measurements on a model of the sluices. This model, built in accordance with the results of the comparative study, was situated in the wind-flume of the "de Voorst" hydraulic laboratory. b. Wave height measurements in the Haringvliet during 1957 and 1958. c. Wind-speed measurements on board the lightship Qoeree, likewise during 1957 and 1958. d. Tidal registrations at Hellevoetsluis from 1920 to 1960. e. Wind-force data from the Hook of Holland, likewise from 1920 to 1960.

scholarly journals SHORELINE ROTATION CAUSED BY LARGE-SCALE EXCAVATION OF REEF FLAT ON SANUR BEACH IN BALI

2011 ◽  
Vol 1 (32) ◽  
pp. 93
Author(s):  
Masatoshi Endo ◽  
Akio Kobayashi ◽  
Takaaki Uda ◽  
Yasuhito Noshi ◽  
Susumu Onaka
Keyword(s):  
Numerical Simulations ◽  
Large Scale ◽  
Reef Flat ◽  
Beach Nourishment ◽  
Beach Erosion ◽  
Field Observations ◽  
Wave Direction ◽  
Bathymetric Survey ◽  
Shoreline Changes ◽  
S Model

In the southern part of Sanur Beach in Bali, beach erosion has occurred between groins after extensive beach nourishment, resulting in shoreline rotation between the groins. The cause of shoreline changes was investigated by field observations, including a bathymetric survey and the sampling of seabed materials, and numerical simulations of beach changes were carried out using Noshi et al.’s model. It was concluded that the shoreline rotation was triggered by the dredging of the reef flat, which caused a change in the wave direction on the reef flat due to the diffraction of waves.

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