Larry F. Bliven

Bio: Larry F. Bliven is an academic researcher from Salisbury University. The author has contributed to research in topics: Sea state & Wavelength. The author has an hindex of 3, co-authored 4 publications receiving 183 citations.

A unified two-parameter wave spectral model for a general sea state

Abstract: Based on theoretical analysis and laboratory data, we proposed a unified two-parameter wave spectral model as is the mean squared surface elevation, and λ0, n0 are the wavelength and frequency of the waves at the spectral peak This spectral model is independent of local wind Because the spectral model depends only on internal parameters, it contains information about fluid-dynamical processes For example, it maintains a variable bandwidth as a function of the significant slope which measures the nonlinearity of the wave field And it also contains the exact total energy of the true spectrum Comparisons of this spectral model with the JONSWAP model and field data show excellent agreements Thus we established an alternative approach for spectral models Future research efforts should concentrate on relating the internal parameters to the external environmental variables

On the Importance of the Significant Slope in Empirical Wind-Wave Studies

Abstract: The significant slope of a random wave field is found to be an important parameter in empirical wind-wave studies. This significant slope Ss is defined as Ss = (ζ2)½/λ0, with ζ2 as the mean-square surface elevation and λ0 as the wavelength corresponding to the waves at the peak of the spectrum. With this parameter, the relationship between Ẽ and n is reduced to an identity expressing a pure geometric measure of the sea state, because Ẽn4 = (2πSs)2. By applying the significant slope as a parameter explicitly, we proposed that the traditional empirical formulas relating the nondimensional energy Ẽ, fetch x and frequency n be combined into a single unified relationship as Ẽn/x = (9/40)Ss9/4. This unified empirical formula governs the wind-wave data equally as well in the field as in the laboratory.

A study on the spectral models for waves in finite water depth

Abstract: From an extension of the Wallops Spectrum (Huang et al., 1981) for the deep water waves, spectral models for waves in finite water depths are developed. Stokes wave expansions are found to offer a good approximation for intermediate water depth. The spectral function in this case is controlled by three parameters: the significant slope, the nondimensional depth, and the peak frequency. It is pointed out that solitary and cnoidal wave models must be used for the shallow water waves. The controlling parameters now reduce to the Urell number and the peak frequency. Even though the resulting spectral models place special emphasis on the energy-containing range of the spectrum, they are not limited to this range and they are not limited to any particular sea state. They are seen as offering a possible explanation of the variations in the special slope observed by previous investigators.

An Experimental Study of the Statistical Properties of Wind-Generated Gravity Waves

Abstract: Statistical properties of wind-generated waves are studied under laboratory conditions. The properties studied include distributions of various zero crossings; crest, trough, and wave amplitudes; local maxima and minima; group length and number of waves per group; and the joint probability distribution of amplitude and period. The results indicate that all the distribution functions are in qualitative agreement with the theoretical expressions derived by Longuet-Higgins in the late 1950s and early 1960s; however, systematic deviations from the results based on a joint Gaussian distribution are apparent. The most likely dynamical reasons for the deviations are: the nonlinear mechanism causing the unsymmetric crest and trough shape, and the breaking of waves. Both of these reasons for deviations are found to be controlled by a single internal variable, the significant slope, defined as the ratio of the rms wave height to the wavelength corresponding to the waves at the spectral peak. The significant slope is also found to be the controlling factor in determining the spectral shape and evolution. Thus, the present set of detailed observational data could be used as the base to link the dynamics and the statistical properties of the wind wave field.

A new view of nonlinear water waves: the Hilbert spectrum

Abstract: We survey the newly developed Hilbert spectral analysis method and its applications to Stokes waves, nonlinear wave evolution processes, the spectral form of the random wave field, and turbulence. Our emphasis is on the inadequacy of presently available methods in nonlinear and nonstationary data analysis. Hilbert spectral analysis is here proposed as an alternative. This new method provides not only a more precise definition of particular events in time-frequency space than wavelet analysis, but also more physically meaningful interpretations of the underlying dynamic processes.

A unified directional spectrum for long and short wind-driven waves

Abstract: Review of several recent ocean surface wave models finds that while comprehensive in many regards, these spectral models do not satisfy certain additional, but fundamental, criteria. We propose that these criteria include the ability to properly describe diverse fetch conditions and to provide agreement with in situ observations of Cox and Munk [1954] and Jahne and Riemer [1990] and Hara et al. [1994] data in the high-wavenumber regime. Moreover, we find numerous analytically undesirable aspects such as discontinuities across wavenumber limits, nonphysical tuning or adjustment parameters, and noncentrosymmetric directional spreading functions. This paper describes a two-dimensional wavenumber spectrum valid over all wavenumbers and analytically amenable to usage in electromagnetic models. The two regime model is formulated based on the Joint North Sea Wave Project (JONSWAP) in the long-wave regime and on the work of Phillips [1985] and Kitaigorodskii [1973] at the high wavenumbers. The omnidirectional and wind-dependent spectrum is constructed to agree with past and recent observations including the criteria mentioned above. The key feature of this model is the similarity of description for the high- and low-wavenumber regimes; both forms are posed to stress that the air-sea interaction process of friction between wind and waves (i.e., generalized wave age, u/c) is occurring at all wavelengths simultaneously. This wave age parameterization is the unifying feature of the spectrum. The spectrum's directional spreading function is symmetric about the wind direction and has both wavenumber and wind speed dependence. A ratio method is described that enables comparison of this spreading function with previous noncentrosymmetric forms. Radar data are purposefully excluded from this spectral development. Finally, a test of the spectrum is made by deriving roughness length using the boundary layer model of Kitaigorodskii. Our inference of drag coefficient versus wind speed and wave age shows encouraging agreement with Humidity Exchange Over the Sea (HEXOS) campaign results.

Directional spectra of wind-generated waves

Abstract: From observations of wind and of water surface elevation at 14 wave staffs in an array in Lake Ontario and in a large laboratory tank, the directional spectrum of wind-generated waves on deep water is determined by using a modification of Barber's (1963) method. Systematic investigations reveal the following: (a) the frequency spectrum in the rear face is inversely proportional to the fourth power of the frequency $\omega $, with the equilibrium range parameter and the peak enhancement factor clearly dependent on the ratio of wind speed to peak wave speed; (b) the angular spreading $\theta $ of the wave energy is of the form sech$^{2}$ ($\beta \theta $), where $\beta $ is a function of frequency relative to the peak; (c) depending on the gradient of the fetch, the direction of the waves at the spectral peak may differ from the mean wind direction by up to 50 degrees, but this observed difference is predictable by a similarity analysis; (d) under conditions of strong wind forcing, significant effects on the phase velocity caused by amplitude dispersion and the presence of bound harmonics are clearly observed and are in accordance with the Stokes theory, whereas (e) the waves under natural wind conditions show amplitude dispersion, but bound harmonics are too weak to be detected among the background of free waves.

Waves in Oceanic and Coastal Waters

Abstract: 1. Introduction 2. Observation techniques 3. Description of ocean waves 4. Statistics 5. Linear wave theory (oceanic waters) 6. Waves in oceanic waters 7. Linear wave theory (coastal waters) 8. Waves in coastal waters 9. The SWAN wave model Appendices References Index.

Similarity of the wind wave spectrum in finite depth water: 1. Spectral form

Abstract: A self-similar spectral shape (the TMA spectrum) to describe wind waves in water of finite depth is presented. The parametric spectral form is depth dependent and an extension of the deep water JONSWAP spectrum. The behavior of the spectrum in frequency and wave number space is discussed. About 2800 spectra selected from three data sets (TEXEL storm, MARSEN, ARSLOE) are investigated to show the general validity of the proposal self-similar spectral shape.