A Parallel Multirate Model of the Scheldt Estuary

Seny, Bruno;Gourgue, Olivier;Lambrechts, Jonathan;Legat, Vincent;Remacle, Jean-François
(2012) 11th International Workshop on Multi-scale (Un)-structured mesh numerical Modelling for coastal, shelf and global ocean dynamics (IMUM2012) — Location: Delft University of Technology, Delft, The Netherlands (28.August.2012)

Files

pres.pdf
  • Restricted Access
  • Adobe PDF
  • 6.32 MB
Request a copy

Details

Authors
Abstract
The development of suitable and fast time integration methods for ocean modeling constitutes an important challenge. No single time-discretization works well for all physical processes in a complex marine model, as dierent subsystems have widely different characteristic time scales. We believe that building appropriate time stepping strategies for multi-scale computations will enable us to gain an order of magnitude. The Second-generation Louvain-la-Neuve Ice-ocean model (SLIM) uses discontinuous Galerkin nite elements on unstructured meshes for the spatial discretization. It is therefore well suited for simulating estuarine and coastal fows where capturing complex topography is crucial. Moreover, unstructured grids also allow to capture a wide spectrum of time and length scales in a single model since the spatial resolution can be increased in regions of interest. Explicit time-stepping methods are very inecient in this framework due to the severe limitation on the time-step enforced by the stability requirements. Multirate schemes present a way to partly circumvent these restrictions by gathering the mesh elements in groups that satisfy the local CFL stability conditions for a certain range of time steps. These methods turn out to be well suited and optimized for the discontinuous Galerkin meshes and may dramatically reduce the total computational efforts for large-scale applications. The parallelization of these methods is challenging since the computational cost varies in space and time. Multi-constrained partitioning strategies are applied to the meshes in order to obtain the best parallel performance. In the context of multi-scale marine modeling, the application of the multirate approach is not limited to the hydrodynamics but also takes into account other hydrological processes such as biological and passive tracers. Moreover, considering wetting and drying areas is also a quite critical challenge for a multirate time stepper. In this framework, the relevance and the performance of the parallel multirate strategy are analyzed for the Scheldt Estuary.
Affiliations

Citations