What is the influence of
indented walls on the oceanic circulation?
Frédéric Dupont, David Straub, Charles Lin
McGill, Dept of Atmo. & Ocean
In most oceanic models, complex basin geometries are approximated by well known step-like (or indented) boundaries. These boundaries present sharp corners at the resolution scale of the model. Thus, there is an unknown risk of amplifying small scale numerical noise. Extending the work of Adcroft and Marshall (1998), we examine if indented walls along the boundary are a suitable approximation for straight walls that are not aligned with one of the coordinate axes. Adcroft and Marshall (1998) used the Munk-Stommel problem as a test case. The physical problem remains identical except for an artificial rotation which only affects the discretization of the square basin. This artificial rotation creates indented walls and has an influence on the general ocean circulation. We propose a similar experiment which compares results from a rotated and non-rotated grid. Here, we consider the dependence of this influence of grid orientation on the circulation as a function of Reynolds number. We are particularly interested in whether numerical problems associated with corners increase or decrease with Reynolds number as higher resolution permits the use of more realistic values for the eddy viscosity. The experiments are performed using a shallow water finite difference code under both slip and no slip conditions.