scholarly journals A STUDY ON WAVE TRANSFORMATION INSIDE SURF ZONE

1966 ◽  
Vol 1 (10) ◽  
pp. 14 ◽  
Author(s):  
Kiyoshi Horikawa ◽  
Chin-Tong Kuo

The wave transformation inside surf zone is treated analytically m this paper under the several appropriate assumptions. The theoretical curves computed numerically have a consistant agreement with the experimental data in the case of wave transformation on a horizontal bottom. On the other hand, m the case of wave transformation on a uniformly sloping beach, the analytical treatment seems to be inadequate to clarify the actual phenomena. Besides them the numerous data on wave height attenuation and others are presented m the graphical forms.

2018 ◽  
Vol 5 (1) ◽  
pp. 119
Author(s):  
Karina Santoso ◽  
I Dewa Nyoman Nurweda Putra ◽  
I Gusti Bagus Sila Dharma

Bali is one of the islands where there are many surf zones with various characteristics. In addition, Bali is also a heaven with a classy wave for the surfers of the world. One of the most challenging places to surf in Bali is Uluwatu Beach. Uluwatu Beach is ranked the 3rd best surf spot in the world version of CNN Travel in 2012. Wind causes sea waves, therefore wind data can be used to estimate the height and direction of the waves. Wave Hindcasting with Sverdrup, Munk and Bretschneider (SMB) method is calculated based on wind data for 10 years (2001 - 2010) from BMKG Ngurah Rai Station - Denpasar to obtain a significant wave height and period. In this research, it is necessary to approach through Hindcasting procedure, wave transformation analysis and surfing Terminology in determining the type of breaking wave and classification of surf zone in Uluwatu Beach area. Wave calculation result in Uluwatu Beach dominated by wave that coming from west side with significant wave height (Hs) of 0.98 m and significant wave period (Ts) of 5.21 s. The wave height due to the influence of wave refraction and shoaling is 0.976 m. The breaking wave height obtained from the calculation is 1.04 m at a depth of 0.849 m. From the result in this research, it can be concluded that the breaking wave type that occurred at Uluwatu Beach is plunging type according to the calculation result from its Irribaren number (0.4 <Ni <2.3). The classification of the surf zone at Uluwatu Beach based on its breakup type of wave is thought to be a good zone for surfers on intermediate level.


2016 ◽  
Vol 858 ◽  
pp. 354-358
Author(s):  
Tao You ◽  
Li Ping Zhao ◽  
Zheng Xiao ◽  
Lun Chao Huang ◽  
Xiao Rui Han

Within the surf zone which is the region extending from the seaward boundary of wave breaking to the limit of wave uprush, breaking waves are the dominant hydrodynamics acting as the key role for sediment transport and beach profile change. Breaking waves exhibit various patterns, principally depending on the incident wave steepness and the beach slope. Based on the equations of conservation of mass, momentum and energy, a theoretical model for wave transformation in and outside the surf zone was obtained, which is used to calculate the wave shoaling, wave set-up and set down and wave height distributions in and outside the surf zone. The analysis and comparison were made about the breaking point location and the wave height variation caused by the wave breaking and the bottom friction, and about the wave breaking criterion under regular and irregular breaking waves. Flume experiments relating to the regular and irregular breaking wave height distribution across the surf zone were conducted to verify the theoretical model. The agreement is good between the theoretical and experimental results.


1986 ◽  
Vol 1 (20) ◽  
pp. 53
Author(s):  
Shigeki Sakai ◽  
Kouestu Hiyamizu ◽  
Hiroshi Saeki

Transformation of irregular waves affected by opposing currents on a sloping sea bed was discussed, experimentally and theoretically. It was found that representative values of wave height, such as a significant wave height, are larger before breaking and the wave height decaying occurs more promptly in a surf zone as opposing currents become dominant, and that characteristics of a irregular wave transformation are determined by the dimensionless unit width discharge q* and the deep water wave steepness. This means that the effects of opposing currents on irregular wave transformation are qualitatively identical to that on the regular waves. A transformation model of irregular waves affected by opposing currents was presented. In the model, formulations for a regular wave transformation, in which the effects of opposing currents were taken into account, were applied to individual waves defined by zero-down" cross-method from irregular wave profiles. Comparisons between experimental results and the prediction by the model showed that the present model gives a good explanation for wave height distributions and the experimental finding that the surf zone is moved offshore by opposing currents.


2012 ◽  
Vol 1 (33) ◽  
pp. 28 ◽  
Author(s):  
Marion Tissier ◽  
Philippe Bonneton ◽  
Gerben Ruessink ◽  
Fabien Marche ◽  
Florent Chazel ◽  
...  

Recent field studies over low sloping beaches have shown that infragravity waves could dissipate a significant part of their energy in the inner surf zone. This phenomenon and the associated short- and long-wave transformations are not well-understood. In this paper, we assess the ability of the fully nonlinear Boussinesq-type model introduced in Bonneton et al. (2011) to reproduce short and long wave transformation in a case involving a strong infragravity wave dissipation close to the shoreline. This validation study, based on van Dongeren et al. (2008)’s laboratory experiments, suggests that the model is able to predict infragravity wave breaking as well as the complex interactions between short and long waves in the surf zone.


Author(s):  
Tai-Wen Hsu ◽  
Ta-Yuan Lin ◽  
Hwung-Hweng Hwung ◽  
Yaron Toledo ◽  
Aron Roland

The combined effect of shoaling, breaking and energy dissipation on a sloping bottom was investigated. Based on the conservation principle of wave motion, a combined shoaling and bottom slope coefficient is included in the mild-slope equation (MSE) which is derived as a function of the bottom slope perturbed to the third-order. The model incorporates the nonlinear shoaling coefficient and energy dissipation factor due to wave breaking to improve the accuracy of the simulation prior to wave breaking and in the surf zone over a steep bottom. The evolution equation of the MSE is implemented in the numerical solution which provides an efficient scheme for describing wave transformation in a large coastal area. The model validity is verified by comparison to accurate numerical models, laboratory experiments and analytical solutions of waves travelling over a steep sloping beach.


Author(s):  
Tai-Wen Hsu ◽  
Kun-Sian Lai

Analytical solutions for wave height decay due to shoaling and breaking on a bar type profile are presented. A macroscopic analogy between an idealized surf zone and a hydraulic jump are incorporated in the theory to account for wave transformation and energy dissipation in the surf zone. The theoretical results are fairly compared with laboratory observations. Key parameters that influence wave energy dissipation in the surf zone are investigated.


2007 ◽  
Vol 588 ◽  
pp. 353-397 ◽  
Author(s):  
O. KIMMOUN ◽  
H. BRANGER

Particle image velocimetry (PIV) measurements were performed in a wave tank under water waves propagating and breaking on a 1/15 sloping beach. The wave transformation occurred in the surf zone over a large domain covering several wavelengths from incipient breaking to swash zone beyond the shoreline. PIV spatial interrogation windows must be small enough to obtain accurate velocities, and one window covers only a small part of the domain. To overcome this problem and to measure the instantaneous velocity field over the whole surf zone area, we have split the full field into 14 overlapping smaller windows of the same size. Local measurements were synchronized with each other using pulsed TTL triggers and wave gauge data. The full velocity field was then reconstructed at every time step by gathering the 14 PIV fields. We then measured the complete space–time evolution of the velocity field over the whole surf zone. We determined also the ensemble-period-average and phase-average components of the flow with their associated fluctuating parts. We used the PIV images and velocity measurements to estimate the void fraction in each point of the surf zone. Special attention was given to the calculation of the spatial derivatives in order to obtain relevant information on vorticity and on the physical terms that appear in the fluctuating kinetic energy transport equation.


1982 ◽  
Vol 1 (18) ◽  
pp. 4 ◽  
Author(s):  
Hajime Mase ◽  
Yuichi Iwagaki

The main purpose of this paper is to propose a model for prediction of the spatial distributions of representative wave heights and the frequency distributions of wave heights of irregular waves in shallow-water including the surf zone. In order to examine the validity of the model, some experiments of irregular wave transformation have been made. In addition, an attempt has been made to clarify the spatial distribution of wave grouping experimentally. Especially the present paper focuses finding the effects of the bottom slope and the deep-water wave steepness on the wave height distribution and wave grouping.


1976 ◽  
Vol 1 (15) ◽  
pp. 32 ◽  
Author(s):  
Toru Sawaragi ◽  
Koichiro Iwata

By wave breaking, an incident monocromatic wave is transformed to a wave composed of its harmonic frequency waves inside a surf zone. Based on a dimensional consideration, the "-1 power law ", the "-2 power law ", the "-2/3 power law " and the "-1/2 power law " on the wave height spectrum ,H(f), are derived as sorts of equilibrium spectra. These spectra except"-l/2 power law" are shown to agree with experimental data.


2012 ◽  
Vol 1 (33) ◽  
pp. 72 ◽  
Author(s):  
Kei Yamashita ◽  
Taro Kakinuma ◽  
Keisuke Nakayama

The internal waves in the two-layer systems have been numerically simulated by solving the set of nonlinear equations in consideration of both strong nonlinearity and strong dispersion of waves. After the comparison between the numerical results and the BO solitons, as well as the experimental data, the internal waves propagating over the uniformly sloping beach are simulated including the cases of the mild and long slopes. The internal waves show remarkable shoaling after the interface touches the critical level. In the lower layer, the horizontal velocity becomes larger than the local linear celerity of internal waves in shallow water just before the crest peak and the position is defined as the wave-breaking point when the ratio of nonlinear parameter to beach slope is large. The ratio of initial wave height to wave-breaking depth becomes larger as the slope is milder and the wave nonlinearity is stronger. The wave height does not increase so much before wave-breaking on the mildest slope.


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