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Applied Math Seminar
Numerical methods for coastal ocean modeling
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In this presentation I will discuss some numerical techniques employed in a parallel Navier-Stokes code that is used to study the dynamics of the coastal ocean. The code employs a numerical discretization of the Navier-Stokes equations with the Boussinesq approximation using a volume-conserving semi-implicit time discretization on an unstructured horizontal grid with layers in the vertical. Momentum is advected with a conservative Eulerian scheme for unstructured grids, and density is advected using a vertically-implicit scheme which guarantees mass conservation. The nonhydrostatic pressure and free-surface are computed with a preconditioned conjugate gradient algorithm, and load balancing and grid-partitioning are managed with the ParMetis (Parallel Graph partitioning and Sparse Matrix Ordering) package. Numerical challenges of ocean modeling will be highlighted with reference to applications of this code to internal waves in Monterey Bay and the South China Sea, secondary circulation in Three-mile slough, the formation of sand ripples on the sea floor, and pollutant transport at Huntington Beach in Southern California. |