Small-Scale Modeling of Waves and Floes in the Marginal Ice Zone

Abstract:

We are conducting a model-based investigation into the small-scale (O(m)) physics of wave-ice floe interaction in the marginal ice zone (MIZ), in order to test and improve parameterizations utilized by large-scale climate models. The presentation will describe the development and validation of a coupled system to track the wave-forced motion of floating objects (collections of bonded particles) and the concurrent effects of the moving objects on the surrounding fluid. NHWAVE, a fully dispersive wave model with a vertical sigma-coordinate, is extended to model moving objects by including vertical boundary fitted meshing and horizontal immersed boundary method. LIGGGHTS, a discrete element granular particle-tracking simulator, is configured to include realistic bonding forces between elements and incorporate velocity and pressure gradient effects from the fluid model.  

Following an overview of the coupled system, validation results will be presented for the standalone wave and ice models. For NHWAVE, model estimates of surface wave patterns generated by oscillating surface objects are compared to LIDAR measurements from corresponding laboratory experiments. For LIGGGHTS, the stress-strain response is measured for collections of bonded particles under tension and/or compression, then compared to available lab and field data. Results will also be presented from simplified MIZ simulations with the coupled system, in which waves pass through groups of rigid ice blocks and their refraction, diffraction, and reflection are measured. Finally, we will provide a preview of an upcoming series of targeted virtual experiments in which momentum/energy exchange between waves and ice floes is measured under varied conditions.