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

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

Evaluation and adaption of the SPH method for hydraulic engineering problems on federal waterways

E. Rustico and J. A. Jankowski

BAW internal R&D-project report, 2010-2016.

Abstract: Smoothed Particle Hydrodynamics (SPH) is a Lagrangian method for fluid dynamic simulations. In the past decades it drew the attention of the scientific community for its versatility and the possibility to simulate complex phenomena such as e.g. surface tension and fluid-solid interactions with floating objects. SPH has in general higher computational requirements than the most common Eulerian methods and several different models have been proposed for the treatment of boundaries, each with advantages and limitations. Continue reading

Efficient river modelling applying subgrid technology (UnTRIM2)

Two subsequent presentations on the 13th UnTRIM Workshop 2016 with the same title Efficient river modelling applying subgrid technology (UnTRIM2), the first part concerning concept and grids, presented by Regina Patzwahl, and the second part concerning results, presented by Jacek A. Jankowski. Continue reading

An efficient semi-implicit subgrid method for free-surface flows on hierarchical grids

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

Abstract: We present a new modelling strategy for improving the efficiency of computationally intensive flow problems in environmental free-surface flows. The approach combines a recently developed semi-implicit subgrid method with a hierarchical grid solution strategy. Continue reading