Andreas Dittrich

Spatial Variability, Mean Drag Forces, and Drag Coefficients in an Array of Rigid Cylinders

Drag forces exerted by single cylinders in an in-line and staggered multicylinder array were measured in a laboratory flume. The measurements were used to investigate the spatial variability of the drag forces, spatially averaged drag forces, and drag coefficients. The results showed that both individual drag forces and drag coefficients varied between ±30% from the spatially averaged mean. The data are also used to test a computational approach for the determination of the mean drag coefficient of multicylinder arrays taking into account the wake flow structure.

Assessment of Morphodynamical Reactions on Redynamisation Measures - Case Study Upper Rhine

The paper reports on the methodology applied to assess the morphodynamical development of a river reach which is planned to be re-dynamised, according to the “INTERREG IVa - Redynamisation of the Old Rhine” project (2009-2012). The river reach is located at the Upper Rhine parallel to the Grand Canal d’Alsace. Most of the discharge is directed through the canal and only a minimum discharge is flowing through the River Rhine. In the ca. 40 km long section morphological features are nowadays absent due to limited sediment supply and transport. A dynamic river bed shall be supported by means of floodplain lowering, sediment deposition and removement of bank protection. The applied methodology combines 3D-numerical modelling of the flow field and stability approaches to assess morphological changes with particular reference to the sediment dynamics and stability of the main channel and the floodplain areas.