Numerical Simulation of a Floater in a Broken-Ice Field: Part I — Model Description

Abstract

This paper presents a novel concept for simulating the ice-floater interaction process. The concept is based on a mathematical model which emphasizes the station-keeping scenario, i.e. when the relative velocity between the floater and the ice is comparatively small. This means that the model is geared towards such applications as dynamic positioning in ice and ice management. The concept is based on coupling the rigid multibody simulations with the Finite Element Method (FEM) simulations. The rigid multibody simulation is implemented through a physics engine which is used to model the dynamic behaviour of rigid bodies which undergo large translational and rotational displacements (the floater and the ice floes). The FEM is used to simulate the material behaviour of the ice and the fluid, i.e. the ice breaking and the hydrodynamics of the ice floes. Within this framework, the physics engine is responsible for dynamically detecting the contacts between the objects in the calculation domain, and the FEM software is responsible for calculating the contact forces. The concept is applicable for simulations in a three-dimensional space (3D). The model described in this paper is divided into two main parts: the mathematical ice model and the mathematical floater model. The mathematical ice model allows modelling both intact level ice and discontinuous ice within a single framework. However, the primary focus of this paper is placed on modelling the broken ice conditions. A floater is modelled as a rigid body with 6 degrees of freedom, i.e. no deformations of the floater’s hull are allowed. Nevertheless, the hydrodynamics of the floater and the ice is considered within the outlined model. The presented approach allows implementing realistic, high fidelity 3D simulations of the ice-fluid-structure interaction process.

A Software Framework for Simulating Stationkeeping of a Vessel in Discontinuous Ice

“…This software development kit (SDK) is used to perform collision detection, contact manifold creation, rigid body and joint dynamics computation, contact force evaluation and time integration of the equations of motion. Metrikin et al (2012b) described a framework for modelling a floating structure in broken ice using a physical engine, and Metrikin et al (2012a) performed a comparative study of different physical engines for simulating ice-structure interactions. Later it was realized that physical engines are being constantly developed and improved, and one solution might become outdated in a very short time.…”

Modeling and Control for Dynamic Positioned Marine Vessels in Drifting Managed Sea Ice

“…However, models applying physics engines have shown great promise for handling this, see e.g. (Lubbad and Løset, 2011), (Metrikin et al, 2012b. As mentioned above, the numerical model described in (Metrikin, 2014) is applied as the process model for DP in managed ice.…”