Green Water on Ship Decks - CESOS - NTNU Greco.pdf · Green Water on Ship Decks Marilena Greco ... The time of bubble fragmentation is ... Impact flows and loads on ship-deck structures,

Green Water on Ship Decks

Marilena Greco

CeSOS, Centre of Excellence for Ships and Ocean Structures, Norway

Steps of Physical Investigation

Water shipping scenarios

Green-water kinematics and loads

Occurrence of impact phenomena

Occurrence of parametric roll

Research Tools: Model Tests

2D fixed structure 3D fixed ships

3D ships: heave & pitch 3D ships: parametric roll

Research Tools: Numerical Methods

Domain-Decomposition strategies

Potential Flow Solver:BEM

Navier-Stokes

Solver Coupling

Potential

Seakeeping

Solver

Shallow-water

approximation

2D Water-on-DECK Experiments

Water-on-Deck Scenarios Dam-Breaking (DB) type

Dam DB

Water-on-Deck Scenarios

Water-on-Deck Scenarios Plunging-wave plus Dam-Breaking (PDB) type

PDB

Water-on-Deck Scenarios Hammer-Fist (HF) type

HF

Water-on-Deck Investigations

PDB type

Most common scenario

PDB Water-on-Deck: Initial stages Initial area of the entrapped cavity

From experiments

Area/f2

m

f

max-f

= (max-f)/cf Kjeldsen & Myrhaug (1979)

PDB Water-on-Deck: Initial stages

Experiments DD BEM-NS results

The time of bubble fragmentation is well predicted




Air as ideal gas + adiabatic law in the cavity Incompressible cavity p=pa in the cavity


PDB Water-on-Deck: Initial stages Full scale versus model scale: cavity shape

From numerics (DD BEM-NS)

m

m

m

m

m

PDB Water-on-Deck: Later stages Water-front velocity

u/[g(max-f)m]0.5

x/ [(max-f)m]

u

x

From experiments

wf

PDB Water-on-Deck: Later stages Flow evolution and interaction with a superstructure

DD BEM-NS Air-water interface



PDB Water-on-Deck: Later stages Pressure on the wall: DD BEM-NS versus experiments

Experiments DD results

Experiments DD results

Water-on-Deck Investigations

HF type

From numerics (Full BEM)

HF Water –on-Deck: Occurrence

Hammer-Fist Type WOD Flow evolution

Full BEM DD results





Water-on-Deck Problem Green-water loads: vertical superstructure

PDB HF

(p-p0)/(gD) (p-p0)/(gD)

From numerics (DD BEM-NS)

Water-on-Deck Scenarios Existence diagram

Water-on-Deck Scenarios Existence diagram

Dam-Breaking events

Plunging wave plus Dam-Breaking events

Hammer-Fist events

Plunging-Wave events

Marintek (2000)

White-Water events

3D Model Tests With Fixed Model

Side View

Incoming wave packet

Freeboard

Deck location

Freeboard exceeded

3D Model Tests Analysis of the Initial stage

Plunging Flow


2-D Tests

Ship Deck

water


Dam-break like flow

Ship Deck

water

2-D Tests

Freeboard exceeded Plunging Flow

Dam-break like flow


3D Model Tests With Fixed Model

Top View, large amplitude

3D Model Tests With Fixed Model Structure of the deck flow

Freeboard exceeded

and plunging flow


Diverted outwards flow


Inner “blunt” structure

Dam-break like front

Transverse flow


Growing of the

Inner “blunt” structure

Circular bow

Elliptic bow

u/[g(H-f)m]0.5

x/ [(H-f)m]

x

From experiments

m=(H-f)/c

Centreline Water-Front Velocity

Maximum Pressure on the Deck

From experiments

Green-Water Loading on the Superstructure

From experiments

3D Water on deck Experiments versus LSeak-NS DD

/ 1.25, 0.22, 0L kA Fr

3D Water on deck: Model Tests vs LSeak-NS DD

Front bow motion

/ 1.25, 0.22, 0L kA Fr

Front bow motion

/ 1.25, 0.22, 0L kA Fr


Front bow motion

/ 1.25, 0.22, 0L kA Fr


Front bow motion

/ 1.25, 0.22, 0L kA Fr


Experiments

3D DD

Side Bottom

Experiments

3D DD

Front bow motion

/ 1.25, 0.22, 0L kA Fr


Front bow motion

/ 1.25, 0.22, 0L kA Fr


Front bow motion

/ 1.25, 0.22, 0L kA Fr


/L=1.25, kA=0.15, Fr=0.189

From 3D Experimetal Video

/L=1.25, kA=0.15, Fr=0.189

High-speed run-up with spray


/L=1.25, kA=0.15, Fr=0.189

WOD from front bow


/L=1.25, kA=0.15, Fr=0.189

WOD from the sides


time

3D Water On Deck: Model Tests vs WNLSeak-SW DD

/L=1.25, kA=0.15, Fr=0.189

wall

/L=1.25, kA= 0.15, Fr= 0.189

waves

Exp.

Num.

Exp.

Num.

Exp.

Num.

Exp.

Num.

Deck Pressure: Model Tests vs WNLSeak-SW DD

wall

Probably due to with-spray jet impact before the main

water reaches the wall

Experiments: Parametric Roll & Water on Deck

FPSO free in heave, pitch and roll

in head sea waves

Front view

Side view

Parametric roll occurrence Numerical (WNLSeak-SW DD) transient phase

/L=1 kA=0.1

T and T4n in the signal T4n=2T in the signal

resonance & instability

T T4n

Front view Top view

Water-on-deck: Model Tests vs WNLSeak-SW DD

/L=0.75 kA=0.25: event after instability

Front view Top view



Front view Top view



Front view Top view



Front view Top view



Front view Top view

/L=0.75 kA=0.25: event after instability 0.5T4n=T


1

2

3

4

5

6

7

Water-on-deck occurrence: Numerical Solution

Influence of parametric roll on the deck pressure

Parametric roll occurrence: Numerical sol. Influence of water-on-deck loads on the instability

This research has been possible especially thanks to:

Dr. Claudio Lugni

CNR-INSEAN & CeSOS

Dr. Giuseppina Colicchio

CNR-INSEAN & CeSOS

Prof. Odd M. Faltinsen

NTNU & CeSOS

All 3D experiments were performed at CNR-INSEAN

Dr. Maurizio Landrini

CNR-INSEAN

Relevant References

Publications on Books •Faltinsen O.M., Greco M., 2011, Slamming and green-water phenomena on ships, in Marine Technology and Engineering:

CENTEC Anniversary Book. Editors: Soares C.G., Garbatov Y., Fonseca N., Texeira A.P., Technical University of Lisbon,

Portugal, Vol. 1.

Publications on International Journals •Colicchio G., Greco M., Lugni C., Faltinsen O.M., 2013, 3D Domain Decomposition for Violent Wave-Ship Interactions, Int. J.

for Numerical Methods in Engineering, accepted for publication.

•Greco M., Bouscasse B., Lugni C., 2012, 3D seakeeping analysis with water on deck and slamming. Part 2: Experiments and

physical investigations, J. of Fluids and Structures, 33.

•Greco M., Lugni C., 2012, 3D seakeeping analysis with water on deck and slamming. Part 1: Numerical solver, J. of Fluids and

Structures, 33.

•Colicchio G., Greco M., Faltinsen O.M., 2011, Domain-Decomposition Strategy for Marine Applications with Cavities

Entrapments, J. of Fluids and Structures, 27 (4).

•Colicchio G., Greco M., Lugni C., Faltinsen O.M., 2010, Towards a fully 3D domain-decomposition strategy for water-on-deck

phenomena, J. of Hydrodynamics, Ser. B, 22 (5).

•Greco M., Colicchio G., Faltinsen O.M., 2007, Shipping of Water on a Two-dimensional Structure: Part II, J. of Fluid

Mechanics, 581.

•Colicchio, G., Greco, M., Faltinsen, O.M., 2006, BEM-level set domain decomposition strategy for nonlinear and fragmented

interfacial flows, Int. Journal Numer. Meth. Engng, 67/10.

•Greco M., Faltinsen O.M., Landrini M., 2005, Shipping of Water on a Two-dimensional Structure, J. of Fluid Mechanics, 525.

•Greco M., Landrini M., Faltinsen O.M., 2004, Impact flows and loads on ship-deck structures, J. of Fluids and Structures, 19 /3.

•Faltinsen O.M., Landrini M., Greco M., 2004, Slamming in marine applications, J. Engng. Math., 48.

•Barcellona M., Landrini M., Greco M., Faltinsen O.M., 2003, An Experimental Investigation on Bow Water Shipping, J. Ship

Res., 47/4.

Green Water on Ship Decks - CESOS - NTNU Greco.pdf · Green Water on Ship Decks Marilena Greco ... The time of bubble fragmentation is ... Impact flows and loads on ship-deck structures,

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