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There can be many benefits of accessing real time accurate estimates of the surrounding wave field for ships and floating structures. This knowledge is important for operational risk mitigation as well as the safety of the vessel and its cargo. In the open literature, wave buoys, ship radars (including X-band and K-band radars) / satellite scanning and hydrodynamic modeling using ship motions seem to be highlighted among the methods to measure / estimate wave field. In the present study, an alternative approach is developed using ship motions and recent developments in artificial intelligence, namely artificial neural networks and machine learning type modelling. In this paper, machine learning approach is introduced briefly, followed by a description of the artificial neural network model used. The paper reports the results obtained for a near shore science vessel in head seas with various ship speeds and sea states. The preliminary results show very good performance in wave field estimation compared to the actual one using machine learning approach with ship motions.

Offshore oil and gas operations are being conducted in harsh environments such as offshore fields around Newfoundland and Labrador. The platforms used in these fields may be exposed to additional risks due the presence of drifting ice pieces in various sizes. To avoid a dangerous collision with a large floating ice, ice management and risk mitigation plans are required firstly. In case of smaller ice pieces (or bergy bits), if they collide with an offshore platform, the combined load of bergy bits and waves may be larger than the typical design wave loads. Hence, it is necessary to predict how these bergy bits may interact with a platform in a given sea state to estimate the combined load for developing a reliable design. In this paper, dynamic interaction between a moving bergy bit and a fixed offshore platform is simulated using CFD (Computation Fluid Dynamics) method. Trajectories and velocities of ice are simulated and compared to understand the hydrodynamic interaction by applying a series of different wave conditions such as wave period, height and relative incident peak location. The simulation outcomes show the importance and possibilities to apply it to the design process of such structures in the ocean., ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering, 17 June 2018, Madrid, Spain

Offshore oil and gas operations conducted in harsh environments such offshore Newfoundland may pose additional risks due to collision of smaller ice pieces and bergy bits with the offshore structures, including their topsides in the case of gravity based structures particularly in extreme waves. In this paper, CFD (Computational Fluid Dynamics) prediction for wave loads acting on a bergy bit around a fixed offshore platform is presented. Often the vertical column of a gravity based structure is designed against ice collisions, if operating in such an environment. In practices, topsides are usually protected by being placed sufficiently high from the still water level, away from the reach of the bergy bits. This vertical clearance between the still water level and the topside deck is known an air gap. Hence, the amount of the air gap planned for such an offshore structure is an important factor for the safety of the topsides at a given location. In this study a CFD method is applied to estimate the dynamic response of the bergy bit and provide a reliable air gap to reduce the potential risk of the bergy bit collision. In advance of more complex collision simulations using a free-floating ice for the airgap design, CFD analysis of wave load prediction on a stationary bergy bit is carried out and reported in this paper. In the experiments and CFD simulations, the location of the bergy bit is changed to quantify the change of wave load due to the hydrodynamic interaction between the bergy bit and the platform. Finally, the results of the CFD simulations are compared with the relevant experiment results to confirm the simulation performance prior to the free floating bergy bit simulations., ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering, 25 June 2017, Trondheim, Norway

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.

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 × 32m × 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., The ASME 35th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2016, June 19-24, 2016, Busan, South Korea

A 3D dispersive numerical model has been developed and utilized to study the interacted wave field in the Offshore Engineering Basin (OEB) of National Research Council Canada in the presence of array of structures. The basic physics of the numerical model follows the concept of the depth averaged velocity distribution along with an enhanced dispersion relation. The Alternating Direction Implicit (ADI) algorithm has been employed for the solution of the governing equations. As an application, the model has been used to study the wave propagation in the presence of different combinations of structures where the effects due to the reflection and diffraction are also incorporated. Relevant experiments are carried out in the OEB. 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 in the OEB at different probe locations for different wave and structure conditions. The comparisons of the numerical results show great agreement with the experimental results. In this paper the results for regular waves will only be presented and discussed., 2014 Oceans - St. John's, OCEANS 2014, 14 September 2014 through 19 September 2014

A mathematical model is established to describe wave-current interaction over uneven sea bottoms. The basic equations of the model are obtained by vertically integrating the continuity equation and the equation of motion for flow over impermeable sea bed of mild slope. Finite difference method is utilized for numerical solutions and the results for a wave-current coexistent field over submerged mound show that the variation of the wave features is fairly significant due to the presence of the current which leads to remarkable drop of the mean water level over the mound and that the waves also affect the mean water level appreciably.

Accurate generation of the primary waves and the reproduction of the group-induced second-order low and high frequency waves have been considered essential for physical i.e. model test in the laboratory. In the laboratory when multi-chromatic primary waves are generated the required bounded waves will be generated naturally at the difference frequencies. In addition to that several unwanted free waves are also generated. The free waves, having the same frequencies of the bounded waves are reproduced due to mismatch of the boundary conditions at the wave paddle. The other two types of free waves are due to the wave paddle displacement and the local disturbances. We carried out physical experiments to identify the second order spurious waves in shallow water in the Offshore Engineering Basin (OEB) at the Institute for Ocean Technology (IOT) of National Research Council (NRC) Canada. In the basin water depths in the range of 0.4m to 0.6m are used for the experiments. The peak wave periods also have varied from 1.133s to 2.145s. In the experiments multi-chromatic waves are used. The drive signals of the wave-makers are generated using first-order and second-order wave generation techniques. Total 14 wave probes are used to capture the data in the wave tank. A NRC-IOT code is used to isolate the primary waves, the bounded waves and the unwanted free waves from the measured data at each wave probe. The measured data are analyzed in this paper to illustrate the differences in the waves generated by two different generation techniques., 30th International Conference on Ocean, Offshore and Arctic Engineering (OMAE2011), 19-24 June 2011, Rotterdam, The Netherlands, Series: ASME Conference Proceedings

Accurate generation of the primary waves and the reproduction of the group-induced second-order low and high frequency waves have been considered essential for physical model test in the laboratory. In the laboratory when bi-chromatic primary waves are generated the required bounded waves will be generated naturally at the difference frequency. In addition to that several unwanted free waves are also generated. The free waves, having the same frequency of the bounded wave are reproduced due to mismatch of the boundary conditions at the wave paddle. The other two types of free waves are due to the wave paddle displacement and the local disturbances. We carried out an extensive experimental program to identify the second order spurious waves in shallow water in the Offshore Engineering Basin (OEB) at the Institute for Ocean Technology (IOT) of National Research Council (NRC) Canada. In the experiments water depths are used in the range of 0.3m to 0.8m. The wave periods also have varied from 0.9s to 2.22s. In the experiments mono- and bi-chromatic waves are used. The drive signals of the wave-maker are generated using first-order and second-order wave generation techniques. Total 14 wave probes are used to capture the data in the wave tank. A NRC-IOT code is used to isolate the primary waves, the bounded waves and the unwanted free waves from the measured data at each wave probe. The measured data are analyzed in this paper to illustrate the differences in the waves generated by two different generation techniques., 29th International Conference on Ocean, Offshore and Arctic Engineering, 6-11 June, 2010, Shanghai, China

A nonlinear numerical model has been formulated to study the propagation of a monochromatic surface wave. The model is formulated through the vertical integration of the continuity equation and the equations of motion. This model is investigated for wave propagation, velocity distribution, energy propagation and varying Courant, Friedrichs and Lewy's (CFL) condition. The applicability of this model for both shallow- and deep-water wave is also examined. The results and analyses are shown in details. The results obtained from the model are compared with the Stokes third-order wave theory and with the relevant experimental data.