Author Archives: jaj

Parallel IO for parallel UnTRIM

Developments concerning the parallel input and output (IO) in the parallel version of UnTRIM with a special attention for its efficiency are presented. The usage of MPI IO (developed ca. 2010) and of the highly specialised libraries like HDF5 or NetCDF (developments in 2018 and 2019) is discussed and assessed from the point of view of engineering practice and the efficiency of parallel IO systems ubiquitous in the present-day high performance computers.

Transparencies for a talk presented on 16th UnTRIM Workshop held in Trento, 13-15th May 2019 are available.

Ten Years After: MPI-UnTRIM’s past and future

The presentation summarizes in a rather informal and philosophical, but thoroughly informative way the development history of the MPI version of UnTRIM ten years after finalizing the parallel code applied subsequently for practical projects at BAW.

Transparencies from the talk delivered on 15th UnTRIM Workshop in Trento (28-30th May 2018) are available.

River computations: artificial backwater from the momentum advection scheme

F.W. Platzek, G.S. Stelling, J.A. Jankowski, R. Patzwahl and J.D. Pietrzak

Abstract: The established method for determining dike heights and dimensioning river training structures is to assess the resulting backwater by numerical modelling. The common consensus is that bottom friction determines the backwater and that momentum advection only has a local effect. We demonstrate that the numerical/artificial backwater contribution from the momentum advection approximation can be of the same order of magnitude as the bottom friction contribution, depending on the advection scheme. Continue reading

Ships in a river and a river with ships – a concept

A concept for a project for a mathematical model for ship-waterway interactions treated in the geophysical mesoscale. i.e with the resolutions typical to geophysical models of water bodies. It is a conceptual work inevitably containing reviews and work results of others with numerous quotations and references. Acknowledgements at the end of the presentation.

In the envisioned approach the waterway is treated equally important as the moving ship, with a holistic approach to natural flows (rivers, channels) and the ship being a disturbance generator as well as an object reacting to the surrounding current. Shores an the bottom of the water body are treated as well as boundary conditions as the objects of an impact by a moving vessel. The formal research domain can be qualified as a ship in confined shallow water, but in this case the confined water body in the presence of ships attracts the equal attention.

Transparencies of the presentation are available, presented on the 14th UnTRIM Workshop in Trento on 15th May 2017.

Ein effizienter semi-impliziter Subgrid-Ansatz für Strömungen mit freier Oberfläche auf hierarchischen Gittern

F.W. Platzek, G.S. Stelling, J.A. Jankowski, R. Patzwahl and J.D. Pietrzak

German Abstract: Es wird eine neue Modellierstrategie zur Effizienzsteigerung rechenintensiver Simulationen von Flüssen vorgestellt. Der Ansatz kombiniert einen semi-impliziten Subgrid-Ansatz zur Berücksichtigung von hochaufgelösten Geländeinformationen auf gröberen Netzen mit einer auf Hierarchischen-Netzen basierenden Strategie. Continue reading