The simulation of violent free-surface dynamics at sea and in space

Non-linear free-surface phenomena, such as extreme waves and violent sloshing, and their impact on the dynamics response of the containing vessels have long been subjects that could only be studied with experimental methods. Nowadays, computational CFD tools can make a significant contribution to these flow problems. The paper starts with a...

Hydrodynamics of wind-assisted ship propulsion verification and validation of RANS methodology

Wind energy as an auxiliary form of propulsion for commercial ships has again become of great interest as a possible response to volatile fuel prices and increasingly stringent environmental regulations. A well-founded performance prediction tool is a key prerequisite for the further development of this promising technology, and with the support...

On the physical mechanisms for the numerical modelling of flows around air lubricated ships

Air lubrication techniques are very promising in reducing ship drag. It has been demonstrated that air cavity applications can realise propulsive power reduction percentages of 10-20% due to the reduction of the frictional resistance [1, 2]. However, a complete understanding of the two-phase flow physics involved with air cavity flows is still...

Validation of a simple aerodynamic model capable to predict the interaction effects occuring between two generic wind propulsion systems

In recent years wind-assisted propulsion for commercial ships has gained an increasing interest as valuable alternative to reduce fuel pollutant emissions. However, the development of feasible and commercially viable wind propulsion systems to partially (or fully) propel a ship is nowadays hindered by the difficulties of modelling the...

An analysis method to evaluate the added resistance in short waves considering bow wave breaking

A bow wave breaking is one of the most prominent factors to be considered regarding the nonlinearity of added resistance for a ship. Considering the stability of the bow wave breaking, which is mostly influenced by the ship speed and the waterline entrance angle, can enhance understanding of the nonlinearity. Understanding of the nonlinearity...

The application of particle image velocimetry for the analysis of high-speed craft hydrodynamics

The particle image velocimetry (PIV) technique has become a reliable method for capturing the velocity field and its derivatives, even in complex flows and is now also widely used for validation of numerical codes. As the imaging system is sensitive to vibrations, the application in environments such as towing tanks makes it a challenging task....

Analysis of green water events on a typical FPSO design

This study dealt with the problems caused by green water waves, waves that reach so high that significant overflow onto the deck occurs. The most important hazard caused by green water is the direct impact load on deck, threatening equipment, hull structure and personnel. The goal of current green water research is to be able to (better) predict...

Analysis of green water events on a typical FPSO design

This study dealt with the problems caused by green water waves, waves that reach so high that significant overflow onto the deck occurs. The most important hazard caused by green water is the direct impact load on deck, threatening equipment, hull structure and personnel. The goal of current green water research is to be able to (better) predict...

Managing Basin Interdependencies in a Heterogeneous, Highly Utilized and Data Scarce River Basin in Semi-Arid Africa: The case of the Pangani River Basin, Eastern Africa

For integrated water resources management both blue and green water resources in a river basin and their spatial and temporal distribution have to be considered. This is because green and blue water uses are interdependent. In sub-Saharan Africa, the upper landscapes are often dominated by rainfed and supplementary irrigated agriculture that...

Systematic Study of Green water and its Impact on Structures

<br/>The Offshore Industry is one of the most challenging industries. Offshore vessels must survive all weather conditions over its lifetime. In heavy storms, waves and ship motions become so large that water flows onto the deck, It is referred to as Green Water and is a serious challenge that needs to be considered in designing offshore vessels...

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...

Screening wave conditions for the occurrence of green water events on sailing ships

Design loads for extreme wave events on ships, such as slamming and green water, are hard to define. These events depend on details in the incoming waves, ship motions and structure layout, which requires high-fidelity tools such as CFD or experiments to obtain the correct loads. These tools (presently) do not have the capability to fully...

Breaking wave impacts on the front deck of a ship: An experimental and numerical study about green water on ships in focused breaking waves

Green water events on ships in extreme waves pose a considerable risk to personal, operational, and structural safety. Considering these issues, novel experiments were done to investigate the interaction between focused breaking waves and a ship at forward speed. The investigated interactions are global motion, global loads, and forces on a deck...

Probability and distribution of green water events and pressures

This article proposes a method to quantify, first, the probability of occurrence of green water and, second, the expected maximum pressures during green water events using their statistical distribution for ships at forward speed. A large green water data set which represents 1945 hours of continuous sailing on full scale with different sea...

The Influence of Aeration and Deadrise Angle on Impact: An experimental and numerical study of the influence of deadrise angle and aeration on maximum impact pressure

When sailing in heavy seas, it happens that the water washes over the bow. This shipping of water is generally divided into two types. The term white water is used when the water is more of a spray and is generally harmless. Green water is more violent and can pose a danger to the crew and structures on board. <br/><br/>Research on green water...

Required test durations for converged short-term wave and impact extreme value statistics — Part 1: Ferry dataset

For the design of maritime structures in waves, the extreme values of responses such as motions and wave impact loads are required. Waves and wave-induced responses are stochastic, so such responses should always be related to a probability. This information is not easy to obtain for strongly non-linear responses such as wave impact forces....

Land surface modeling informed by earth observation data: toward understanding blue–green–white water fluxes in High Mountain Asia

Mountains are important suppliers of freshwater to downstream areas, affecting large populations in particular in High Mountain Asia (HMA). Yet, the propagation of water from HMA headwaters to downstream areas is not fully understood, as interactions in the mountain water cycle between the cryo-, hydro- and biosphere remain elusive. We review...