Exceedance frequency of appearance of the extreme internal waves in the World Ocean

Statistical estimates of internal waves in different regions of the World Ocean are discussed. It is found that the observed exceedance probability of large-amplitude internal waves in most cases can be described by the Poisson law, which is one of the typical laws of extreme statistics. Detailed analysis of the statistical properties of internal waves in several regions of the World Ocean has been performed: tropical part of the Atlantic Ocean, northwestern shelf of Australia, the Mediterranean Sea near the Egyptian coast, and the Yellow Sea.</p

Internal breathers' loads on marine facilities

We study interaction of long internal breathers in the idealized conditions, which correspond to realistic summer density stratification in the western part of the Cyprus coastal waters near the offshore gas fields. According to the maps of nonlinear and kinematic parameters of internal waves, which have been produced in our earlier studies, in this region the coefficient of cubic nonlinearity in the Gardner equation is positive. Therefore, breathers of internal waves can be generated in such a medium, for example, during the degeneration of long disturbances (from tidal or atmospheric sources). A series of numerical experiments on the interaction of breathers in the framework of the Gardner equation was carried out. Statistical moments up to the fourth order were calculated, and spectral analysis of the interaction process was provided. The structure of the velocity field induced by internal breather as well as the corresponding loads upon underwater engineering constructions are determined

Particle transport by internal breathers

The processes of particle transport induced by internal breathers in quasi three-layer fluid are investigated in the framework of weakly nonlinear theory. We use the Gardner equation to describe the displacement at the maximum of vertical baroclinic mode. To determine the fields of vertical and horizontal velocities, which are used for calculating of Lagrangian particle trajectories, we apply three versions of the wave fields' vertical structure: linear mode, weakly nonlinear approximation (with taking into account the first nonlinear correction to linear mode) and weakly nonlinear-weakly dispersive approximation (with taking into account both the first nonlinear correction and the first dispersive correction to linear mode). The processes of particle transport are investigated for different initial configurations of breathers, as the velocity fields induced by nonlinear wave packets are substantially different for breathers with different phases. The comparison of the form of particle trajectories for different horizons and different breathers' configurations is made. It is shown that the use of the weakly nonlinear model is sufficient to determine the trajectories of fluid particles. Taking into account the first dispersive correction to the modal function almost does not affect particles' displacements, neither qualitatively, nor quantitatively. A significant difference between solutions of the problem of fluid particles' trajectories for two types of nonlinear wave motions in a stratified fluid-solitons and breathers-is revealed

Impact of IW-induced currents on submersed pillars

We study the influence of intensive internal gravity waves, which are generated from baroclinic tidal wave and disturbances related to the variations in atmospheric pressure, on the hypothetic pillars of marine structures. We use temperature and salinity vertical profiles from GDEM climatology in a region near the Zohr offshore natural gas field located in the Egyptian sector of the Mediterranean Sea. Investigation of internal waves' dynamics was carried out in the framework of program complex intended for numerical modelling of propagation and transformation of such waves in the ocean, that implements procedure of numerical integration of fully nonlinear two-dimensional (vertical plane) system of equations of hydrodynamics of inviscid incompressible stratified fluid in the Boussinesq approximation bearing in mind the forcing by barotropic tide. The variations of the horizontal and vertical velocities are studied. Morison's formula is used to calculate the pressure force on the lateral surface of the elongated cylinder (pile). In the framework of this approach flow pressure contains the inertial (linear, depending on the acceleration of fluid particles in the wave) and the drag (non-linear resistance force, quadratic in velocity) components. It is shown that the inertial force is mainly smaller in absolute value than the drag force. A distribution of the loads and torques upon unit length of the pillar in time is considered

Impact of IW-induced currents on submersed pillars

We study the influence of intensive internal gravity waves, which are generated from baroclinic tidal wave and disturbances related to the variations in atmospheric pressure, on the hypothetic pillars of marine structures. We use temperature and salinity vertical profiles from GDEM climatology in a region near the Zohr offshore natural gas field located in the Egyptian sector of the Mediterranean Sea. Investigation of internal waves' dynamics was carried out in the framework of program complex intended for numerical modelling of propagation and transformation of such waves in the ocean, that implements procedure of numerical integration of fully nonlinear two-dimensional (vertical plane) system of equations of hydrodynamics of inviscid incompressible stratified fluid in the Boussinesq approximation bearing in mind the forcing by barotropic tide. The variations of the horizontal and vertical velocities are studied. Morison's formula is used to calculate the pressure force on the lateral surface of the elongated cylinder (pile). In the framework of this approach flow pressure contains the inertial (linear, depending on the acceleration of fluid particles in the wave) and the drag (non-linear resistance force, quadratic in velocity) components. It is shown that the inertial force is mainly smaller in absolute value than the drag force. A distribution of the loads and torques upon unit length of the pillar in time is considered

Particle transport by internal breathers

The processes of particle transport induced by internal breathers in quasi three-layer fluid are investigated in the framework of weakly nonlinear theory. We use the Gardner equation to describe the displacement at the maximum of vertical baroclinic mode. To determine the fields of vertical and horizontal velocities, which are used for calculating of Lagrangian particle trajectories, we apply three versions of the wave fields' vertical structure: linear mode, weakly nonlinear approximation (with taking into account the first nonlinear correction to linear mode) and weakly nonlinear-weakly dispersive approximation (with taking into account both the first nonlinear correction and the first dispersive correction to linear mode). The processes of particle transport are investigated for different initial configurations of breathers, as the velocity fields induced by nonlinear wave packets are substantially different for breathers with different phases. The comparison of the form of particle trajectories for different horizons and different breathers' configurations is made. It is shown that the use of the weakly nonlinear model is sufficient to determine the trajectories of fluid particles. Taking into account the first dispersive correction to the modal function almost does not affect particles' displacements, neither qualitatively, nor quantitatively. A significant difference between solutions of the problem of fluid particles' trajectories for two types of nonlinear wave motions in a stratified fluid-solitons and breathers-is revealed