Deformation of the Wave Field Interacting With Offshore Platforms: Comparison Between the Corresponding Results From a Numerical Model and a Wave Tank

In the present research, a 3D dispersive numerical model has been developed and utilized to study the modification of the wave field in the presence of offshore structure. The Alternating Direction Implicit (ADI) algorithm has been employed for the solution of the governing equations. Relevant experiments are carried out in the Offshore Engineering Basin (OEB) of National Research Council (NRC) Canada. OEB is a 3D heavy duty 75m 7 32m 7 2.8m test facility equipped with modern data acquisition and tracking devices to record experimental data. Total 10 wave probes are deployed to measure the data at different locations in the Basin. Later the numerical results are compared with the experimental results. The comparisons of the numerical results show great agreement with the experimental results.Peer reviewed: YesNRC publication: Ye

Transformation of mono- and multi-chromatic water waves propagating from a Quasi-deepwater to a shallow water region.

A vertically integrated 3D numerical model that uses the concept of depth average velocity distribution with enhanced dispersion characteristics investigates the propagation and transformation of mono- and multi-chromatic waves from a quasi-deep region to shallow water region. A finite difference method has been employed for the numerical computation that follows ADI (Alternating Direction Implicit) algorithm. The local sea bottom is uneven and turns into a moderately shallow water due to presence of a ridge-like bottom near the coast. The bottom configuration is from a location off Nova Scotia coast in Canada. Detail results and discussions are presented.Peer reviewed: NoNRC publication: Ye

OMAE2009-80104 TRANSFORMATION OF MONO-AND MULTI-CHROMATIC WATER WAVES PROPAGATING FROM A QUASI-DEEPWATER TO A SHALLOW WATER REGION

ABSTRACT A vertically integrated 3D numerical model that uses the concept of depth average velocity distribution with enhanced dispersion characteristics investigates the propagation and transformation of mono-and multi-chromatic waves from a quasi-deep region to shallow water region. A finite difference method has been employed for the numerical computation that follows ADI (Alternating Direction Implicit) algorithm. The local sea bottom is uneven and turns into a moderately shallow water due to presence of a ridge-like bottom near the coast. The bottom configuration is from a location off Nova Scotia coast in Canada. Detail results and discussions are presented

Loading due to interaction of waves with colinear and oblique currents

A study on the loading of an oblique surface wave and a surface current field on a fixed vertical slender cylinder in a 3D flow frame is illustrated in the present paper. The three dimensional expressions describing the characteristics of the combined wave-current field in terms of mass, momentum and energy flux conservation equations are formulated. The parameters before the interaction of the oblique wave-free uniform current and current-free wave are used to formulate the kinematics of the flow field. These expressions are also employed to formulate and calculate the loads imparted by the wave-current combined flow on a bottom mounted slender vertical cylinder. In the present study two different situations are assumed where current is uniform over depth and also acting over a layer of fluid that extends from the free surface to a specified finite depth. In this paper we extend the approach considered in Zaman and Baddour (2004) for the wave-current analysis. Morison et al. (1950) equation is deployed for the load computations in all cases. The above models are utilized to compute the loads and moments on a slender cylinder for a wave with varying range of incidence current field.Peer reviewed: YesNRC publication: Ye

Behavior of the residual wave components in a 3D wave basin after the termination of the wave maker

After the termination of the wave making, the characteristics of the existing wave components in a 3D large scale Offshore Engineering wave Basin (OEB) at the National Research Council of Canada have been investigated experimentally. In the generation of any wave in the tank we get the relevant primary wave components along with bounded wave components if the incident primary wave has more than one frequency. Inevitably we also get interacted wave components, natural frequency components of the tank and other free waves. In this paper the tank's natural frequency components, bounded wave components and other free waves after the termination of wave making were investigated using several cases of mono- and bi-chromatic waves. These component energies were then compared with the total energy of the measured primary waves. The magnitudes of the residual undulations are also investigated for mono-, bi- and multichromatic waves over different time segments. Several sets of wave data are analysed to perceive the energy due to natural frequency of the basin, energy transferred to the side bands and the damping rate of the residual waves in the tank with respect to the chosen incident wave conditions. In the analysis it is observed that the energy damping rate varies with the incident wave condition but seems much faster than that of 20 minutes traditional waiting time in between two runs in the OEB. The energies for tank's natural frequency components and other free waves were found to be very small compare to the incident primary wave energies.Peer reviewed: YesNRC publication: Ye