Motion based cable integrity limits for quadrant assisted pull-in operations on submarine inter-array cables

The installation of subsea cables connecting offshore wind turbines to the grid is a delicate process. This is especially the case for the operation of connecting the second end of the cable to the turbine. The applied method of using a quadrant means that in the workability analyses, multibody dynamics, line dynamics and sea state dynamics need...

A hydrodynamic analysis of three floating offshore wind-wave energy converters differing in the floating stability principle

A significant percentage of the offshore wind resource is located in waters deeper than 60m. Therefore, several floating offshore wind turbines (FOWT) have been conceived in recent years. In deep waters, it seems logical to also harvest wave energy. One of the options to harness both resources is to use a floating offshore hybrid wind-wave...

An investigation of numerical analysis for modeling free-surface elevation from flow over a shallowly submerged 2D naca0012 hydrofoil

The bulbous bow is a common feature for large displacement vessels. The purpose of the bulbous bow is to reduce the bow wave, hereby making use of wave cancellation theory. The main drawback of these type of bows is that the drag reduction effect is only present for a limited range of sailing speeds. If the transit velocity is altered, the...

Ballast for Lifting: A novel lifting method for topsides of offshore platforms

Amazing Grace will be needed for the removal of offshore platforms that are out of Pioneering Spirit 's reach. The base case design of Amazing Grace is an enlarged version of Pioneering Spirit (Figure 1). Amazing Grace uses mainly Quick drop Ballast tanks, releasing a lot of water at once, for lifting. Pioneering Spirit uses mainly a pneumatic...

A two-dimensional boundary element method for floating cylinders of arbitrary shape in frequency domain with power take off and second order predictions

A two-dimensional (2D) panel method is developed to find the first and second order wave forces acting on a semi-submerged cylinder in regular waves. The panel method is based on potential flow and the waves are modeled for both finite and infinite water depth. The motion is limited to heave, but allows for extensions to other modes as well. It...

Internal Loads of Semi-Submersibles at an Inconvenient Draft: An investigation into the non-linear response

Once a semi-submersible is operating at an inconvenient draft (A shallow draft with limited water column above the pontoons), the passing waves over the pontoons can not keep their linear motion and energy will be transferred to higher harmonic wave frequencies. This means the hydrodynamic response will also contain energy at these higher...

Hydro-elasticity of a Bulge Wave Energy Converter in the 2D Frank Close-Fit Method

Hydro-elasticity is important in the evaluation of a category of wave energy converters (WEC). In this paper, the hydro-elastic response of a bulge wave energy converter is examined by the implementation of a two-dimensional potential theory. The numerical implementation of the Frank Close-Fit method (FCFM) defines hydrodynamic coefficients and...

Numerical modelling of aerated-water wave impacts

A substantial part of structural damage for conventional vessels is caused by complex free surface events like slamming, breaking waves and green water. These events lead to the interaction of air and water where air can be entrained in water. The resulting air bubbles can considerably affect the evolution of the pressure caused by hydrodynamic...

Drift Force Numerical Simulation of a Vertical Wall and a Sphere in Regular Waves

Mooring system is one of the critical parts of a floating system in an offshore environment. It can be compromised by the wave drift force that exerts a considerable amount of load due to its non-linear properties. Due to the increase in complexity of the analysis, a numerical method is often opted to conduct the simulation of the wave drift...

Quantification of Thruster Forces for Escorting Tugs

DAMEN tugs can be found in nearly any port or terminal around the world. Operating in ports and terminals requires the tugs to be highly efficient in ship handling in order to quickly escort larger vessels. To predict the escort capabilities of a tug, DAMEN has developed the computer program DAMEN TUGSIM. Since the tool is becoming a decisive...

3DP: A control system model for combined DP station keeping and active roll reduction

A conventional dynamic positioning system is used to control vessel motions in the horizontal plane, i.e. surge, sway and yaw. However, the safety and operability of several offshore operations can be increased when also the roll motion is actively controlled, especially in beam seas. A control system model is proposed for combined thruster...

Monopile installation assessment: A critical assessment of an oscillating monopile during offshore installation

An offshore wind turbine requires a stable support structure to support the tower and nacelle. The support structure in the form of a monopile is lowered to the seabed and hammered in the soil. During the lowering process the monopile may show excessive motions, that occur on an irregular basis. The cause for this is unknown. This thesis is...

Real-time numerical modeling of subsea cable dynamics – Visualized in Augmented Reality

There lies an opportunity for significant cost savings in the installation of subsea cables in offshore wind farms which is why the current work proposes a state-of-the-art method for monitoring the cable during installation. The proposed method enables offshore crew to look through the water with the use of augmented reality. To this end a real...

Analytical Modelling of Fluid-Structure Interaction: On Developing Equations to Understanding Rizos' Experiment (2016)

The activities of humans in the marine environment are on a steady rise; this trend follows the exposure of offshore structures and vessels to harsh environmental conditions. On the other hand, there is continuous demand for lighter, faster and more efficient vessels. Technological advancement in composite materials and better design methods...

Numerical Simulation of the Interaction of A Membrane with Water with A Free Surface: Simulation of An Experiment by L. Rizos

In order to collect validation data for the study of the mechanism of fluid-structure interaction (FSI), an lab experiment was conducted by L. Rizos in the towing tank, 3ME,TUDelft in 2016. The concept of the experiment is shown in the figure 1. A cylindrical container is partially filled with water. A small cylindrical oscillator with flexible...