Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Numerical Investigation into the Effects of Layer and Accumulated Ice Floes on the Hydrodynamics
Performance of the Damaged Ship
XinLong Zhang1, Simone Mancini2, Ping Li1
1: College of Shipbuilding Engineering, Harbin Engineering University, Harbin, Heilongjiang province, China
2: Department of Hydro and Aerodynamics, Force Technology, Kgs. Lyngby, Denmark

It requires that the damaged ship must be able to return to a port without
external assistance. Therefore, it is necessary to assess the stability of thedamaged ship in any potential sea conditions. In recent years, owing to
the improvement of the computation power, the dynamic stability
analysis of the damaged ship based on CFD has been extensively studied
in the open sea condition. The relevant hydrodynamic behaviors
including the flooding process and the motion responses were recentlyinvestigated, for instance, by Manderbacka (2019).
Zhang (2020a, 2020b, 2021) investigated the effects of the damage
position and the flooding form on the flooding process and motions ofthe damaged ship. The Volume of Fluid (VOF) method is applied tocapture the flooding process, while the Unsteady Reynold-Averaged
Navier-Stokes (URANS) solver is used to deal with the ship’s motions.
The simulation results show that even though the damaged compartment
is the same, the dynamic responses caused by the damage positions aredifferent. And, compared to symmetric flooding, asymmetric flooding
will generate an excessive roll angle, threatening the safety of thedamaged ship. Moreover, due to the obstruction of the compressed air in
the flooded compartments, the expected symmetric flooding form would
eventually become the asymmetric flooding.
To analyze the effects of air compressibility on the flooding process,Gao (2018) set different ventilation levels for a damaged compartment,
including the airtight level, partial ventilation level and full ventilationlevel. The simulation results indicate that the limited ventilation level
will delay the flooding process and reduce the flooding volume. Ming(2018) applied a weakly compressible Smoothed Particle
Hydrodynamics (SPH) method to analyze the effects of the beam wave’sdirection on the motions of the damaged ship. It can be found that when
the beam waves are towards the damaged side, the damage opening
would be lifted away from the free surface. As a result, the flooding
velocity is slower than that in the beam waves towards the intact side.
And, the flooding amount in the flooded compartment is less. SadatHosseini (2016) assessed URANS capabilities for hydrodynamic
behaviors of a zero-speed damaged passenger ship, including theflooding procedure in calm water, roll decay in calm water, and motions
in regular beam waves for various wavelengths. The results show thateven though the computational effort of CFD simulation is high, thepredicting motion responses match well with the experimental data. In
general, the dynamic behaviors of the damaged ship in the open sea canbe well studied and understood based on the above-introduced methods.

ABSTRACTDue to the acceleration of global warming, the shrinkage of the compact
ice-covered area allows the ice-going ship to transport through the Polar
Sea Route. Collisions, naval operations, and fatigue would potentiallycause hull deformation and damage. To better improve the safety of thepolar ship in any extreme sea condition, this paper demonstrates thecapability for the simulation of ship-ice-flooding interactions in stillwater. The main purpose is to investigate the effects of the ice floes andconcentration on the flooding process and motion responses of thedamaged ship. Computational Fluid Dynamics (CFD) is used to govern
the fluid flow and motions of the damaged ship, while the Discrete
Element Method (DEM) is applied to deal with the ice particle dynamics.
Part injector and random injector are introduced to define the distributionof the ice floes. Three typical sea scenarios are simulated to perform thecomparing analysis, including the open sea, the layer ice floes and theaccumulated ice floes. Through the captured flooding process, thedynamic interactions between the ice floes and hull can be visualized.
From the obtained simulation results, it can be found that the movement
process of the ice floes in the damaged compartment can be divided into
three stages, including the ice floes accumulation, the ice floes collapsing
and the ice floes dispersion. Since the upright layer ice floes are more
likely to be pushed underwater, the roll motion wouldn’t be affected
much. However, the accumulated ice floes in close contact can provide
efficient support for the hull, the roll amplitude of the damaged ship canbe reduced. Moreover, for the accumulated ice floes scenario, theblocking effect near the damage opening is more obvious. In general, theproposed simulation method can provide a valuable reference for further
investigations for the design of the polar ship or vessels that will operateon polar seas.

KEY WORDS: Global warming; Ice floes; Damaged ship; Flooding
process; Motion response; CFD simulations.

INTRODUCTION
Damage stability is of high priority in the ship design. TheInternational Maritime Organization (IMO) issued a safety regulation forpassenger ships entitled the Safe Return to Port (SRtP) (Spanos, 2012).

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