Non-hydrostatic Unified Model of the Ocean with Application to Ice/ocean Interaction Modeling

The non-hydrostatic unified model of the ocean (NUMO) has been developed to advance model capability to realistically represent the dynamics and ice/ocean interactions in Greenland fjords, including an accurate representation of complex fjord geometries. To that end, NUMO uses high-order spectral element methods on unstructured grids to solve the incompressible Navier–Stokes equations complemented with heat and salinity transport equations. This paper presents the model’s description and discusses the formulation of ice/ocean Neumann boundary conditions based on the three-equation model. We validate the model on a range of test cases. The convergence study on the classical Kovasznay flow shows exponential convergence with arbitrary basis function polynomial order. The lock-exchange and density current cases show that the model results of buoyancy-driven flows solved with 2D and 3D unstructured meshes agree well with previously published findings. Finally, we show that a high-order simulation of an ice block immersed in saline water produces results that match both direct numerical simulation and laboratory experiments.