This page has only limited features, please log in for full access.
For centuries, scientists have been attempting to map complex hydraulic processes to empirical formulas using different flow resistance definitions, which are further applied in numerical models. Now questions arise as to how consistent the simulated results are between the model dimensions and what influence different morphologies and flow conditions have. For this reason, 1D, 2D and 3D simulations were performed and compared with each other in three study areas with up to three different discharges. A standardized, relative comparison of the models shows that after successful calibration at measured water levels, the associated 2D/1D and 3D/1D ratios are almost unity, while bed shear stresses in the 3D models are only about 62–86% of the simulated 1D values and 90–100% in the case of 2D/1D. Reasons for this can be found in different roughness definitions, in simplified geometries, in different calculation approaches, as well as in influences of the turbulence closure. Moreover, decreasing 3D/1D ratios of shear stresses were found with increasing discharges and with increasing slopes, while the equivalent 2D/1D ratios remain almost unchanged. The findings of this study should be taken into account, particularly in subsequent sediment transport simulations, as these calculations are often based on shear stresses.
Kurt Glock; Michael Tritthart; Helmut Habersack; Christoph Hauer. Comparison of Hydrodynamics Simulated by 1D, 2D and 3D Models Focusing on Bed Shear Stresses. Water 2019, 11, 226 .
AMA StyleKurt Glock, Michael Tritthart, Helmut Habersack, Christoph Hauer. Comparison of Hydrodynamics Simulated by 1D, 2D and 3D Models Focusing on Bed Shear Stresses. Water. 2019; 11 (2):226.
Chicago/Turabian StyleKurt Glock; Michael Tritthart; Helmut Habersack; Christoph Hauer. 2019. "Comparison of Hydrodynamics Simulated by 1D, 2D and 3D Models Focusing on Bed Shear Stresses." Water 11, no. 2: 226.
In dieser Arbeit werden verschiedene Methoden zur numerischen Modellierung des Sedimenttransports basierend auf dreidimensionaler Hydrodynamik auf großen, mittleren und kleinen Skalenebenen erörtert und deren Eignung für ingenieurmäßige Aufgabenstellungen anhand von konkreten Anwendungsfällen beleuchtet. Auf der großen Skalenebene kommt das BOKU-Sedimenttransportmodell iSed zum Einsatz, das auf der Lösung der Strömungsgleichungen mittels des Reynolds-Averaged-Navier-Stokes-Verfahrens (RANS) basiert. Als Anwendungsfall dieses Modells dienen Prozesse des Geschiebetransports und der Morphodynamik bei verschiedenen Buhnengeometrien an der österreichischen Donau. Auf der mittleren Skalenebene wird ein neu entwickeltes Geschiebetracermodell präsentiert, mit dem bevorzugte Pfade des Geschiebes an der Gewässersohle erkannt und in ingenieurtechnische Planungsaufgaben einbezogen werden können; dieses Modell wurde an einem weiteren Donauabschnitt eingesetzt und erfolgreich an Naturmessdaten validiert. Abschließend wird ein kleinskaliges Modell eines sphärischen Einzelkorns präsentiert, welches es mittels der hochauflösenden Large-Eddy-Simulation (LES) ermöglicht, turbulente Wirbelstrukturen und damit in Zusammenhang stehende Druckfelder abzubilden. Modellierungen dieser Art tragen wesentlich dazu bei, zukünftig verbesserte, auf mechanischen Ansätzen basierende Geschiebetransportmodelle zu entwickeln. This work addresses different methods for the numerical modelling of sediment transport based on three-dimensional hydrodynamics on large, medium and small scales and discusses their relevance for engineering tasks exemplified by specific applications. On the large scale the BOKU sediment transport model iSed is applied, which is based on the solution of the governing equations of flow using the Reynolds-Averaged Navier-Stokes (RANS) method. Modelled processes of sediment transport and morphodynamics related to various groyne geometries at the Austrian Danube are presented as an example. On the medium scale a newly developed pebble tracer model is presented that allows to identify preferred paths of bedload at the river bed, which can be taken into consideration for planning tasks in engineering; this model was applied to a further reach of the Danube River and successfully validated using field data. Finally a small-scale model of a spherical single grain is presented which allows to reproduce turbulent flow structures and related pressure fields by using the high-resolution Large-Eddy simulation technique (LES). Models of this kind contribute substantially to the future development of improved bedload transport models based on fundamental principles of mechanics.
Michael Tritthart; Kurt Glock; Martin Glas; Sencer Yücesan; Marcel Liedermann; Philipp Gmeiner; Christoph Hauer; Helmut Habersack. Erfahrungen in der numerischen Sedimenttransportmodellierung auf unterschiedlichen Skalen – von RANS bis LES. Österreichische Wasser- und Abfallwirtschaft 2019, 71, 170 -178.
AMA StyleMichael Tritthart, Kurt Glock, Martin Glas, Sencer Yücesan, Marcel Liedermann, Philipp Gmeiner, Christoph Hauer, Helmut Habersack. Erfahrungen in der numerischen Sedimenttransportmodellierung auf unterschiedlichen Skalen – von RANS bis LES. Österreichische Wasser- und Abfallwirtschaft. 2019; 71 (3-4):170-178.
Chicago/Turabian StyleMichael Tritthart; Kurt Glock; Martin Glas; Sencer Yücesan; Marcel Liedermann; Philipp Gmeiner; Christoph Hauer; Helmut Habersack. 2019. "Erfahrungen in der numerischen Sedimenttransportmodellierung auf unterschiedlichen Skalen – von RANS bis LES." Österreichische Wasser- und Abfallwirtschaft 71, no. 3-4: 170-178.
As is widely known, the groyne layout affects the three-dimensional flow situation and sediment budget in groyne fields. Lack of knowledge exists concerning the evolution of hydrodynamics and morphodynamics in the main channel of rivers due to distinct groyne layouts. Accordingly, the sensitivity of the stream flow and the river bed in the fairway to groyne geometry were investigated with the help of a three-dimensional hydrodynamic model and a sediment transport model by considering eight variants and seven discharges in a straight reach of the River Danube. The variation of crest elevation and length indicated highest sensitivity, especially at modelled discharges for which the largest geometrical changes due to the modification of the groyne layout were implemented. Within a curved reach larger effects for length variation and smaller ones for the variation of crest elevation were found. These findings can be incorporated into future research and planning of groyne layouts.
Martin Glas; Kurt Glock; Michael Tritthart; Marcel Liedermann; Helmut Habersack. Hydrodynamic and morphodynamic sensitivity of a river’s main channel to groyne geometry. Journal of Hydraulic Research 2018, 56, 714 -726.
AMA StyleMartin Glas, Kurt Glock, Michael Tritthart, Marcel Liedermann, Helmut Habersack. Hydrodynamic and morphodynamic sensitivity of a river’s main channel to groyne geometry. Journal of Hydraulic Research. 2018; 56 (5):714-726.
Chicago/Turabian StyleMartin Glas; Kurt Glock; Michael Tritthart; Marcel Liedermann; Helmut Habersack. 2018. "Hydrodynamic and morphodynamic sensitivity of a river’s main channel to groyne geometry." Journal of Hydraulic Research 56, no. 5: 714-726.
Shallow water depths in the southern arm of a widely intact bifurcation zone in the Lower Danube lead to a detour for navigation of ∼110 km on the way to the Black Sea at low discharges. In this study, different conceptual hydraulic engineering measures have been assessed with the goal of increasing the water depths in the southern arm, thereby also considering a minimized impact on fish migration (in particular sturgeons). The effects of the different measures were analysed based on a 3D hydrodynamic numerical model (RSim-3D) and a sediment transport model (iSed). The results show that transverse structures in the northern arm, dredging operations in the southern arm as well as a spur dike at the bifurcation might not lead to the desired success. The most promising alternative considering water depths for navigation and fish migration might be a modification of the river course.
Kurt Glock; Michael Tritthart; Philipp Gmeiner; Sebastian Pessenlehner; Helmut Habersack. Evaluation of engineering measures on the Danube based on numerical analysis. Journal of Applied Water Engineering and Research 2017, 7, 48 -66.
AMA StyleKurt Glock, Michael Tritthart, Philipp Gmeiner, Sebastian Pessenlehner, Helmut Habersack. Evaluation of engineering measures on the Danube based on numerical analysis. Journal of Applied Water Engineering and Research. 2017; 7 (1):48-66.
Chicago/Turabian StyleKurt Glock; Michael Tritthart; Philipp Gmeiner; Sebastian Pessenlehner; Helmut Habersack. 2017. "Evaluation of engineering measures on the Danube based on numerical analysis." Journal of Applied Water Engineering and Research 7, no. 1: 48-66.