Discrete-element model for the interaction between ocean waves and sea ice

Abstract

We present a discrete-element method (DEM) model to simulate the mechanical behavior of sea ice in response to ocean waves. The interaction of ocean waves and sea ice potentially can lead to the fracture and fragmentation of sea ice depending on the wave amplitude and period. The fracture behavior of sea ice explicitly is modeled by a DEM method where sea ice is modeled by densely packed spherical particles with finite sizes. These particles are bonded together at their contact points through mechanical bonds that can sustain both tensile and compressive forces and moments. Fracturing naturally can be represented by the sequential breaking of mechanical bonds. For a given amplitude and period of incident ocean waves, the model provides information for the spatial distribution and time evolution of stress and microfractures and the fragment size distribution. We demonstrate that the fraction of broken bonds α increases with increasing wave amplitude. In contrast, the ice fragment size l decreases with increasing amplitude. This information is important for the understanding of the breakup of individual ice floes and floe fragment size.

A Discrete Element Model of Armor Glass Fragmentation and Comminution Failure Under Compression

“…A similar treatment also has been applied to describe the interparticle bonding interaction. As brittle failure is the primary focus of this study, the cohesive bond between two particles represented by an elastic spring element is assumed to break when its finite strength is exceeded: …”

“…The glass then is quasi-statically compressed from the left at a nominal strain rate of 0.001/s. Table I summarizes the model parameters used for the current numerical demonstration, where the spring constants associated with the contact force formulation were estimated following k cn = Ed and k ct = (k cn /2 (1 + m)) 30 and adopting typical material properties of borosilicate glass. 35,36 The same correlation was further postulated for the cohesive shear and normal bond strength as T = (Σ/2(1 + m)) with Σ calibrated based on the experimentally measured tensile strength.…”

A discrete-element model for viscoelastic deformation and fracture of glacial ice

“…There are also some models developed within the field of glaciology, which are specific to ice. A few models exist for the pure elastic behavior with fracture [8] and [9], and Ref. [10] describes a model, where individual ice elements can deform plastically, but cannot move relative to each other without permanent breakup.…”

A Coupled System for Investigating the Physics of Wave–Ice Interactions

“…Earlier models (e.g., Hopkins and Shen 2001;Hopkins and Thorndike 2006) represent each complete ice floe as a single element of O(100-1000) m and are applied to larger domains, such as Cook Inlet, Alaska. More recent DEM efforts (e.g., Xu et al 2012;Polojärvi and Tuhkuri 2013;Herman 2013Herman , 2017Orzech et al 2014;Song et al 2014) utilize collections of smaller bonded elements [O(cm-m)] to represent floes or sections of ice. While in general more expensive computationally, this approach allows for investigation of smaller-scale ice floe material properties and behavior in response to wave forcing.…”