Three‐dimensional CFD modeling of morphological bed changes in the Danube River

Abstract

[1] The bed changes in a section of the river Danube were computed using a 3-D computational fluid dynamics model. A time series of discharges during the flood in 2002 was used. The results compared reasonably well with regular bed level surveys before and after the flood. The Danube River section was 6 km long and located between Vienna and the Austrian-Slovakian border. The fully three-dimensional numerical model solved the Navier-Stokes equations using the k-epsilon turbulence closure. Nonuniform sediment transport was computed using the formulas of Wu et al. (2000b), considering hidingexposure algorithms. Both bed deformation and sorting processes were calculated. A number of parameter sensitivity tests were carried out on roughness values, parameters in the sediment transport capacity formula, parameters in the hiding-exposure formulas, critical Shields number, and variations in the formulas for the effect of a sloping bed. Additionally, the sediment inflow to the section was varied together with investigations of physical parameters such as vegetation and groyne structures. The results were most sensitive to the Shields number for critical movement of the sediments. An error analysis was performed to give a quantitative assessment of the parameter sensitivity tests.

Accuracy and comparison of standard k-ϵ with two variants of k-ω turbulence models in fluvial applications

“…In largescale fluvial simulations a minimum number of vertical layers required to cover the three-dimensionality of the flow is reported in literature, e.g. five (Fischer-Antze, Olsen, & Gutknecht, 2008;Fischer-Antze, Rüther, Olsen, & Gutknecht, 2009) to eight layers as reported by Tritthart et al (2011). However, when the model is applied to smaller scales, due to the lack of proper near-wall treatment algorithms and refinement, the results tend to diverge from the measured values.…”

Effect of point bar development on the local force balance governing flow in a simple, meandering gravel bed river

“…Although more complex 2-D and 3-D computational fluid dynamics models have been developed and used to simulate sediment transport and morphologic evolution in rivers [e.g., Li et al, 2008;Fischer-Antze et al, 2008], a relatively simple, quasi-3-D model in which the bed and banks were fixed was sufficient for our purposes here. The objective of this study was not to evaluate a particular numerical model or to use such a model to predict channel change.…”

“…Another, more recent modeling strategy involves two-and three-dimensional computational fluid dynamics [e.g., Shimizu et al, 1990;Ferguson et al, 2003;Duan and Julien, 2005;Ruther and Olsen, 2007]. These numerical flow simulations have been coupled with models of bed material transport [e.g., Li et al, 2008;Vasquez et al, 2008] and bank erosion [e.g., Mosselman, 1998;Darby et al, 2002;Rinaldi et al, 2008] as a means of predicting the evolution of channel form [e.g., Fischer-Antze et al, 2008].…”

Understanding flood regime changes in Europe: a state-of-the-art assessment

“…The hydraulic resistance of submerged vegetation may exhibit complex patterns which are not fully understood and represent an active area of research (Stephan and Gutknecht, 2002;Green, 2005;Nepf, 2012). In addition, the roughness of the streambed may change depending on the sediment size distribution (Fischer-Antze et al, 2008). Roughnesses are usually obtained by calibration, i.e.…”