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1
Content available remote Dependence of acoustic noise emission on the dissipated energy of plunging waves
Klusek Zygmunt, Paprota Maciej, Sulisz Wojciech, Zdolska Aneta, Sorek Sebastian
Oceanologia
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2020
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No. 62 (1)
70--82
EN
The results of experiments performed in a wave flume designed to explore associations between the dissipation of surface wave energy during breaking and acoustic noise emission are presented. The experiments were carried out using tap water in the wave laboratory of the Institute of Hydro-Engineering of the Polish Academy of Sciences, Gdańsk, Poland. In particular, being shown are the parameters of empirical dependency between the dissipated wave energy during plunging and the energy of pre-breaking wave trains. Relationships between wave energy losses in the case of breakers with an amplitude of about 10 cm and the noise acoustic energy in the frequency band from 80 to 12,500 Hz were estimated. Taking into consideration the phenomena of reverberations and propagation in an acoustical waveguide, a numerical model was used for the correction of the observed noise's acoustic spectra. A detailed analysis of the factors affecting the noise level in the semi-enclosed volume allowed us to specify the rate of conversion of the wave energy dissipated during breaking into acoustic energy, which was found to be in the order of 10−8.
2
Content available remote On the nonlinear internal waves propagating in an inhomogeneous shallow sea
Massel S. R.
Oceanologia
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2016
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No. 58 (2)
59--70
EN
A concept of conservation of energy flux for the internal waves propagating in an inhomogeneous shallow water is examined. The emphasis is put on an application of solution of the Korteweg–de Vries (KdV) equation in a prescribed form of the cnoidal and solitary waves. Numerical simulations were applied for the southern Baltic Sea, along a transect from the Bornholm Basin, through the Słupsk Sill and Słupsk Furrow to the Gdańsk Basin. Three-layer density structure typical for the Baltic Sea has been considered. An increase of wave height and decrease of phase speed with shallowing water depth was clearly demonstrated. The internal wave dynamics on both sides of the Słupsk Sill was found to be different due to different vertical density stratification in these areas. The bottom friction has only negligible influence on dynamics of internal waves, while shearing instability may be important only for very high waves. Area of possible instability, expressed in terms of the Richardson number Ri, is very small, and located within the non-uniform density layer, close to the interface with upper uniform layer. Kinematic breaking criteria have been examined and critical internal wave heights have been determined.
3
Content available Wave transformation in a multi-bar surf zone: case study of Lubiatowo (Poland)
Lan Y. J., Hsu T. W., Ostrowski R., Szmytkiewicz M.
Archives of Hydro-Engineering and Environmental Mechanics
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2016
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Vol. 63, nr 1
19--34
EN
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.
4
Content available remote Acoustic noise generation under plunging breaking waves
Klusek Z., Lisimenka A.
Oceanologia
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2013
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No. 55 (4)
809--836
EN
The paper presents results of investigations performed in a wave channel in order to determine associations between the dissipation of surface wave energy during breaking and acoustic noise emission. The experiments were carried out in fresh water in the Large Wave Flume (GWK) at the Forschungszentrum Küste (FZK) in Hanover (Germany). Relationships between the acoustic noise energy and losses of surface wave energy were estimated over the broad acoustic frequency band from 350 to 12 500 Hz, and the characteristic temporal changes of the spectral properties of noise in the breaking process were demonstrated. It was found that the ratio of acoustic noise energy generated during wave breaking to the energy dissipation of single plunging breakers with heights of 1.6-2.8 m were in the 10-9- 10-8 range and found to be in reasonable agreement with the results of some previous experiments performed for smaller scales of breaking wave. The study contributes to the development of a passive acoustic method for the parameterization of sea surface dynamic processes.
5
Content available remote Experimental study of the formation of steep waves and breakers [commun.]
Massel S.R., Tęgowski J., Chomka M., Wichorowski M., Dąbrowski J., Stansberg C. T., Moe V.
Oceanologia
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2001
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No. 43 (3)
353-363
EN
Breaking waves (whitecaps) are one of the most important and least understood processes associated with the evolution of the surface gravity wave field in the open sea. This process is the principal means by which energy and momentum are transferred away from a developing sea. However, an estimation of the frequency of breaking waves or the fraction of sea surface covered by whitecaps and the amount of dissipated energy induced by breaking is very difficult to carry out under real sea conditions. A controlled experiment, funded by the European Commission under the Improving Human Potential Access Infrastructures programme, was carried out in the Ocean Basin Laboratory at MARINTEK, Trondheim (Norway). Simulation of random waves of the prescribed spectra by wave makers provided a very realistic pattern of the sea surface. The number of breaking waves was estimated by photographing the sea surface and recording the noise caused by the breaking waves. The experimental data will serve for calibration of the theoretical models of the sea surface fraction related to the whitecaps.
6
Content available On the relationship between wave breaking and marine aerosol concentration in deep sea areas
Massel S.
Archives of Hydro-Engineering and Environmental Mechanics
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2001
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Vol. 48, nr 2
31-45
EN
Aerosol fluxes from the sea surface are one of the important factors determining the dynamics of the air-sea interaction. Not numerous available data showed that the intensity of aerosol fluxes strongly depends on the intensity of wave breaking. In the paper theoretical formulas to determine the probability of breaking crests and percentage of whitecaps coverage are discussed. These formulas are a starting basis for the set-by-step procedure to determine the aerosol fluxes in deep water under the steady sea state conditions.
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