R. Patzwahl, J.A. Jankowski, T. Lege
Abstract. The paper discusses the advantages and disadvantages of numerical modelling of rivers with a grid of very high resolution using the new MPI version of UnTRIM as the computational engine. The main aim of the investigation is to assess the economy of this approach taking especially into account the effort required for the mesh generation and its modification, which is usually laborious in the case of coarser meshes requiring exact reproduction of structure lines defining the flow. In the first step the results of a low-resolution Telemac-2D grid are compared to the results obtained for the same river stretch topography with a high-resolution UnTRIM model. In the second step the results of two- and three-dimensional modelling applying a high-resolution mesh based on a high quality digital terrain model are studied. It is concluded that under the assumption of appropriate computational resources readily available, the high-resolution modelling reduces significantly the effort required for the initial model set-up and for adjustments due to changes in the model topography. The calibration, parametrisation and validation of the models is simplified without affecting the accuracy, freeing the engineer to concentrate on the project aims and not bypass the weak points of the methodology.
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Reference: R. Patzwahl, J.A. Jankowski, T. Lege (2008) Very high resolution numerical modelling for inland waterway design. In: International Conference on Fluvial Hydraulics (River Flow 2008), Izmir, Turkey, 2008.