Method of Studying Modulation Effects of Wind and Swell Waves on Tidal and Seiche Oscillations

This paper describes a method for identifying modulation effects caused by the interaction of waves with different frequencies based on regression analysis. We present examples of its application on experimental data obtained using high-precision laser interference instruments. Using this method, we illustrate and describe the nonlinearity of the change in the period of wind waves that are associated with wave processes of lower frequencies—12- and 24-h tides and seiches. Based on data analysis, we present several basic types of modulation that are characteristic of the interaction of wind and swell waves on seiche oscillations, with the help of which we can explain some peculiarities of change in the process spectrum of these waves.

Investigation of Seiche Oscillations in the Adjacent Bays by the Example of the Sevastopol and the Quarantine Bays

Purpose. The paper is aimed at studying the seiche structure in the adjacent bays' system of real configuration. Methods and Results. The response of the Sevastopol and Quarantine bays (Black Sea) to sea level fluctuations set at the open boundary of the computational domain has been studied. A number of random harmonics within the range of the eigen periods of these bays were used as fluctuations. The ADCIRC numerical model was applied for simulating. The numerical experiments were performed for three ranges obtained from the analytical estimates: 30–52, 8–30 and 1–15 min. The energy-bearing periods of seiche oscillations were revealed for both bays. The mutual influence of these bays was also studied. Conclusions. The above mentioned wave disturbances lead to generation of the seiche oscillations in the bays. For the Sevastopol Bay, their periods are 48, 22, 16, 10 and 6 min, for the Quarantine Bay – 11.4 and 4.8 min. The number of the generated modes is determined by the interval of the wave disturbance periods. The bays have a mutual influence on each other due to the wave energy exchange through their entrances. At that intensity of the eigen modes of the Sevastopol Bay penetrating the Quarantine Bay can exceed intensity of those of the Quarantine Bay. In both bays, the seiches with the largest amplitudes are induced by the disturbances, the periods of which are in the interval 30–52 min.

Seiches in Petrozavodsk bay of the lake Onego

The analysis of observation data on fluctuations in the level and velocity of currents in the Petrozavodsk Bay of Lake Onega, performed in 2016–2017, was carried out. Level oscillations were measured with a discreteness of 10 s using two TDR-2050 devices (RBR Ltd., Canada). Spectral analysis was performed using the simple Fourier transform method after one-minute data averaging to reduce instrument noise. Energy-carrier periods corresponding to the seiches of Petrozavodsk Bay and the Lake Onega are identified. Current velocities were measured with Aquadopp HR-Profiler (Nortek, Norway). Within the framework of the linear long wave theory, seiche oscillations are considered in a model basin approximating the Petrozavodsk Bay with regard to the Ivanovskiye Islands. Using an analytical solution, estimates for the periods of the higher seiche modes and the corresponding maximum wave flow velocities are obtained for the Petrozavodsk Bay. The comparison of theoretical estimates with the data of field observations, was showed satisfactory agreement.

Influence of atmospheric fronts on free and forced oscillations of the level in the Sea of Azov

The influence of inhomogeneous moving atmospheric pressure fields on currents and free and forced oscillations of the level of the Sea of Azov, induced by constant wind, is studied by the method of mathematical modeling. The hypothesis about the role played by a resonant mechanism in the occurrence of extremely high amplitudes of surge and seiche oscillations, generated by the baric field moving at a speed equal to that of a free long wave, is tested. It is found that, under the same wind, baric disturbances moving over the Sea of Azov induce forced oscillations, and after the disturbances stop, they induce free ones with amplitudes that are higher by 14% than those obtained at constant atmospheric pressure. It is shown that the baric front movement (speed and time of its movement are selected under the assumption that waves with maximum amplitudes are generated) plays an important role in the formation of the current structure and level oscillations in the Sea of Azov.

VESSEL-INDUCED SURGE MODEL VALIDATION IN A COMPLEX HARBOR USING FIELD MEASUREMENTS AND AIS DATA

Large ships moving in narrow waterways generate complex hydrodynamic phenomena, which can cause extreme forces and moments on berthed vessels, and damage shoreline structures and marine habitat. Deep-draft vessels can generate complex phenomena such as bow solitary waves, broken supercritical bore waves, and ship-induced harbor seiche/oscillations. Particular focus is paid in the present paper to simulation and validation of the Vessel Hydrodynamics Longwave Unsteady (VH-LU) modeling system (Fenical et al. 2006) for these complex hydrodynamic phenomena, in particular sloshing and resonance of vessel-induced waves in the complex harbor of Port Canaveral, FL. This paper summarizes two field measurement campaigns and utilization of high-resolution AIS data to provide detailed input for model validation. Analysis indicates that the modeling system is able to reproduce water level oscillations generated by individual vessels, oscillation interactions within the harbor, and interactions between separate basins in the harbor over time. Previous publications have provided limited information on validations performed with the VH-LU modeling system (e.g. Fenical et al. 2011). The model has been shown to accurately reproduce hydrodynamics and berthed vessel forces on tankers in open water conditions, hydrodynamics and loads on berthed Panamax container ships against a vertical quay wall, and supercritical flow and broken bore formation and propagation. This paper will summarize the complete range of model validations with the highest-quality openly available laboratory data, and provide recommendations for future studies and research based on observed needs from practical applications.