SC²S Colloquium - April 29, 2015

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Date: April 29, 2015
Room: 02.07.023
Time: 3:00 pm, s.t.
Invited by: Nikola Tchipev, Kaveh Rahnema

Benedikt Jaeger: Expansions for the Fast Multipole Method

The Fast Multipole Method is an efficient algorithm to solve N-body problems up to a prescribed precision. Here, an implementation of the algorithm with Castesian coordinates is presented. The implementation is validated and compared to another one using spherical harmonics. Also, some ways are described how to optimize the program, amongst others by using a code generator to unroll loops. At last the implementation is tested against the state-of-the-art ExaFMM implementation.

Philipp Samfaß: A Non-Hydrostatic Shallow Water Model on Triangular Meshes in Sam(oa)^2

For the simulation of tsunamis, the hydrostatic shallow water equations have established as a sound mathematical basis. However, due to the hydrostatic assumption, not all relevant physical effects—especially in coastal areas—can be modelled accurately. In this talk, a non-hydrostatic shallow water model is presented for the PDE-framework sam(oa)^2. After a short review of the fractional step approach used for solving the modified non-hydrostatic shallow water equations, a dual grid discretization of the non-hydrostatic pressure equation on adaptive triangular meshes is explained. This discretization allows solving the system of linear equations for the non-hydrostatic pressure correction term using a matrix-free method. Finally, the results obtained with the new model are shown for some common non-hydrostatic validation test cases.