scholarly journals A NUMERICAL MODEL OF NEARSHORE CURRENTS BASED ON A FINITE AMPLITUDE WAVE THEORY

1986 ◽  
Vol 1 (20) ◽  
pp. 64 ◽  
Author(s):  
Masataka Yamaguchi
Keyword(s):  
Numerical Model ◽  
Surf Zone ◽  
Wave Theory ◽  
Quantitative Agreement ◽  
Finite Amplitude ◽  
Wave Transformation ◽  
Current Profile ◽  
Nearshore Currents ◽  
Wave Nonlinearity ◽  
Wave Induced

A numerical model of wave-Induced nearshore currents taking into account the finite amplitude effect is developed, with a cnoidal wave theory used for the estimation of wave characteristics. The model is applied to the computation of wave transformation and nearshore currents on uniformly sloping beaches and on two-dimensional model topographies. The comparison with the results obtained by a linear model shows that wave nonlinearity has a strong influence on wave transformation in shoaling water and in the surf zone and on the strength of nearshore circulation, but that it does not have much effect on the longshore current profile. Moreover, the validity of the present model is supported by the quantitative agreement with the experiment for wave height variations, and the qualitative correspondence with the experiment for mean water level variation and longshore currents and the observation for nearshore currents.

Effects of Cnoidal Wave-Induced Seepage on Vertical Breakwater Resting on Permeable Elastic Seabed

2014 ◽  
Vol 716-717 ◽  
pp. 284-288
Author(s):  
Jian Kang Yang ◽  
Hua Huang ◽  
Lin Guo ◽  
Jing Rong Lin ◽  
Qing Yong Zhu ◽  
...  
Keyword(s):  
Shallow Water ◽  
Wave Theory ◽  
Cnoidal Wave ◽  
Load Prediction ◽  
Wave Load ◽  
Seepage Pressure ◽  
Theoretical Investigations ◽  
Nonlinearity Effect ◽  
Wave Nonlinearity ◽  
Wave Induced

Theoretical investigations on cnoidal waves interacting with breakwater resting on permeable elastic seabed are presented in this paper. Based on the shallow water reflected wave theory and Biot consolidation theory on wave-induced seepage pressure, the analytical solutions to first order cnoidal wave reflection and wave-induced seepage pressure are obtained by the eigenfunction expansion approach. Numerical results are presented to show the effects of depth of water, breakwater geometry on cnoidal wave-induced seepage uplift force and overturning moment. Compared with Airy wave theory, in certain shallow water conditions, the shallow water wave theory can more effectively illustrate wave nonlinearity effect in wave load prediction.

scholarly journals ON THE CHOICE OF RANDOM WAVE SIMULATION IN THE SURF ZONE PROCESSES

2011 ◽  
Vol 1 (32) ◽  
pp. 71
Author(s):  
Jing Yuan ◽  
Ole S. Madsen
Keyword(s):  
Surf Zone ◽  
Transport Model ◽  
Bedload Transport ◽  
Random Wave ◽  
Spectral Approach ◽  
Wave Approach ◽  
Bedload Sediment ◽  
Set Up ◽  
Wave Nonlinearity ◽  
Wave Induced

In this paper, the two common approaches to account for wave randomness, the spectral approach and the wave-by-wave approach, are compared through numerical experiments conducted with the coupling of a surf zone hydrodynamic model and a bedload sediment transport model. Special attention is paid to the wave nonlinearity and net cross-shore bedload transport predictions. The two approaches are found to have negligible difference in their predictions of certain average hydrodynamics, such as wave heights, set-up and undertow. However, the wave-by-wave approach outperforms the spectral approach in the wave nonlinearity prediction, and the two approaches differ significantly in their predictions of wave-induced net cross-shore bedload transport which strongly depends on wave nonlinearity. This suggests the necessity of using the wave-by-wave approach. The computational efficiency of the wave-by-wave approach is also discussed.

scholarly journals A NUMERICAL INVESTIGATION OF THE LONGSHORE CURRENT PROFILE FOR MULTIPLE BAR/TROUGH BEACHES

1986 ◽  
Vol 1 (20) ◽  
pp. 73 ◽  
Author(s):  
Steven K. Baum ◽  
David R. Basco
Keyword(s):  
Numerical Model ◽  
Wave Height ◽  
Water Depth ◽  
Balance Equation ◽  
Surf Zone ◽  
Momentum Balance ◽  
Longshore Current ◽  
Current Profile ◽  
Momentum Balance Equation ◽  
Wave Decay

A numerical model is developed which calculates the longshore current profile for an arbitrary bottom profile. The basis of the model is the use of radiation stress theory in a longshore momentum balance equation which includes a driving stress, a bottom stress, and a lateral mixing stress. Each of the stresses is derived from previously developed formulations, rederiving them to take into account separate cross shore variations in the wave height and the water depth, as well as the wave approach angle. This is done to dispense with the constant wave breaking index assumption used to model wave decay in the surf zone, which is rejected as unrealistic for natural beaches. A numerical model is used to calculate distributions of the wave height and water depth across the surf zone for arbitrary, yet realistic, bottom profiles. A numerical model of the theoretically derived longshore momentum balance equation is developed and solved using the distributions obtained from the wave decay model. The profiles calculated are compared to previous theoretical models and to laboratory and field measurements.

scholarly journals COUPLING STOKES AND CNOIDAL WAVE THEORIES IN A NONLINEAR REFRACTION MODEL

1988 ◽  
Vol 1 (21) ◽  
pp. 42
Author(s):  
Thomas A. Hardy ◽  
Nicholas C. Kraus
Keyword(s):  
Nonlinear Refraction ◽  
Wave Model ◽  
Wave Theory ◽  
Quantitative Agreement ◽  
Wave Mode ◽  
Finite Amplitude ◽  
Second Order ◽  
Stokes Wave ◽  
Linear Wave ◽  
Cnoidal Wave

An efficient numerical model is presented for calculating the refraction and shoaling of finite-amplitude waves over an irregular sea bottom. The model uses third-order Stokes wave theory in relatively deep water and second-order cnoidal wave theory in relatively shallow water. It can also be run using combinations of lower-order wave theories, including a pure linear wave mode. The problem of the connection of Stokes and cnoidal theories is investigated, and it is found that the use of second-order rather than first-order cnoidal theory greatly reduces the connection discontinuity. Calculations are compared with physical model measurements of the height and direction of waves passing over an elliptical shoal. The finite-amplitude wave model gives better qualitative and quantitative agreement with the measurements than the linear model.

scholarly journals A Numerical Model of the Wave-Induced Currents in the Turbulent Coastal Zone

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
O. Fahmy ◽  
K. M. Fassieh ◽  
M. A. Zaki
Keyword(s):  
Numerical Model ◽  
Water Waves ◽  
Surf Zone ◽  
Nonlinear Partial Differential Equations ◽  
Initial Boundary ◽  
Initial Boundary Value Problem ◽  
Coastal Protection ◽  
Protection Measures ◽  
Induced Currents ◽  
Wave Induced

A numerical model is developed, validated and applied to the turbulent coastal currents. The currents are driven by the sea surface slope and the radiation stresses of water waves. They are resisted by friction due to turbulent eddies and sea bottom. The k-ε model is used to model the turbulent stresses. Five simultaneous nonlinear partial differential equations govern the depth-averaged dynamics in the surf zone. An implicit finite-difference scheme is used to obtain an accurate numerical solution of the resulting initial-boundary value problem. It is tested against the case of straight coast with uniform bottom slope and a protective jetty. To investigate the actual wave-induced currents, the model is applied to simulate the currents for three real case studies. Results show that the model could be used to compute currents caused by the constructing coastal protection measures and could predict the locations of accretion and scouring.

scholarly journals WAVE RUN-UP ON A NATURAL BEACH

1988 ◽  
Vol 1 (21) ◽  
pp. 10
Author(s):  
Mitsuo Takezawa ◽  
Masaru Mizuguchi ◽  
Shintaro Hotta ◽  
Susumu Kubota
Keyword(s):  
Surf Zone ◽  
Wave Theory ◽  
Transformation Model ◽  
Wave Transformation ◽  
Electromagnetic Current ◽  
Swash Zone ◽  
Reflected Waves ◽  
Wave Heights ◽  
Run Up ◽  
Incident Waves

The swash oscillation, waves and water particle velocity in the surf zone were measured by using 16 mm memo-motion cameras and electromagnetic current meters. It was inferred that incident waves form two-dimensional standing waves with the anti-node in the swash slope. Separation of the incident waves and reflected waves was attempted with good results using small amplitude long wave theory. Reflection coefficient of individual waves ranged between 0.3 and 1.0. The joint distribution of wave heights and periods in the swash oscillation exhibited different distribution from that in and outside the surf zone. This indicates that simple application of wave to wave transformation model fails in the swash zone.

scholarly journals A NUMERICAL MODEL OF NEARSHORE CURRENTS DUE TO IRREGULAR WAVES

1988 ◽  
Vol 1 (21) ◽  
pp. 83 ◽  
Author(s):  
Masataka Yamaguchi
Keyword(s):  
Numerical Model ◽  
Water Level ◽  
Wave Height ◽  
Wave Model ◽  
Irregular Waves ◽  
Wave Transformation ◽  
Level Variation ◽  
Water Level Variation ◽  
Mean Water Level ◽  
Nearshore Currents

This paper presents a numerical model of nearshore currents due to irregular waves. The radiation stress is estimated by a current-depth refraction model for irregular waves, in which the energy dissipation due to wave breaking is modeled through the use of a saturated frequency spectrum in shallow water. The model is in reasonable agreement with measured wave height, mean water level variation and observed nearshore current patterns. Next, the model is applied to the computation of wave transformation and nearshore currents on a uniformly sloping beach and on model topographies with complicated contour lines. Comparison with the results based on a regular wave model shows that wave irregularity has a smoothing effect on cross-shore distributions of wave height, mean water level variation and longshore currents, but that it does not have much effect on nearshore current patterns.

The coastal refraction-diffraction wave propagation model

1995 ◽  
Vol 17 (4) ◽  
pp. 6-12
Author(s):  
Nguyen Tien Dat ◽  
Dinh Van Manh ◽  
Nguyen Minh Son
Keyword(s):  
Wave Propagation ◽  
Field Data ◽  
Surf Zone ◽  
Propagation Model ◽  
Wave Transformation ◽  
Diffraction Effect ◽  
Linear Wave ◽  
Diffraction Wave ◽  
Linear Wave Propagation ◽  
Wave Propagation Model

A mathematical model on linear wave propagation toward shore is chosen and corresponding software is built. The wave transformation outside and inside the surf zone is considered including the diffraction effect. The model is tested by laboratory and field data and gave reasonables results.

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