On the Evolution of Different Types of Green Water Events

Abstract

Green water events may present different features in the initial stage of interaction with the deck of a structure. It is therefore important to investigate the evolution of different types of green water, since not all the events interact with the deck at the same time. In this paper, the evolution of three types of green water events (dam-break, plunging-dam-break, and hammer-fist) are studied. The water surface elevations and volumes over the deck in consecutive green water events, generated by incident [wave trains in a wave flume, were analyzed using image-based methods. The results show multiple-valued water surface elevations in the early stage of plunging-dam-break and hammer-fist type events. Detailed experimental measurements of this stage are shown for the first time. The effect of wave steepness on the duration of the events, maximum freeboard exceedance, and volumes were also investigated. Although the hammer-fist type showed high freeboard exceedances, the plunging-dam-break type presented the largest volumes over the deck. Some challenges for further assessments of green water propagation are reported.

On the Evolution of Different Types of Green Water Events—Part II: Applicability of a Convolution Approach

“…This paper, therefore, aims to explore the applicability of the advectiondiffusion analytical convolution approach proposed by [36] to represent the temporal variation of SVWS elevations found in the initial stages of different types of green water events (mainly PDB and HF types). The paper is an extension of previous work by [19], who reported details of the initial stages of different types of green water events experimentally. The present study is a first attempt to identify the possibilities of the practical implementation of an analytical model that is able to capture SVWS elevations, as well as to identify challenges for further research to capture MVWS elevations.…”

“…Shipping water events can occur in different ways, depending on the wave features and the shape and operational conditions of the structure [17][18][19]. The study of water shipping on structures, or green water events, as this is known in ocean and offshore engineering [11,18], requires evaluation for different flooding scenarios.…”

“…Until now, the applicability of most common analytical models has been tested against single-valued water surface (SVWS) elevation measurements, obtained from experiments (using cameras or wave gauge sensors) or numerical simulations (e.g., [18,24,30,32,36]). However, Fontes et al [19] showed that in PDB and HF events, multiple-valued water surface (MVWS) elevations occur at a specific position over the deck (see stage 4 in Figure 1b,c). More information about the SVWS and MVWS definitions can be found in [19,42].…”

“…However, Fontes et al [19] showed that in PDB and HF events, multiple-valued water surface (MVWS) elevations occur at a specific position over the deck (see stage 4 in Figure 1b,c). More information about the SVWS and MVWS definitions can be found in [19,42].…”

“…Comparisons between analytical models and experiments have been performed, considering time series of SVWS elevations at equidistant positions over the deck of the structures. However, it has recently been reported [19,25] that interesting features are found in the initial stages of shipping water, where MVWS elevations occur. The performance of analytical convolution models to capture shipping water elevations of different types of green water events in these initial stages had not been tested-a possibility for future research [24].…”