Cases of dam failure occur around the world almost each year. Dam failures can result in the formation and propagation of fast-moving unsteady flows that can cause loss of life as well as significant environmental and economic consequences in downstream flooded areas. The initial stages of a dam break are important due to wave-breaking front and the associated turbulence. Furthermore, characteristics of the river bed downstream of the dam (topography and bathymetry) as well as the presence of obstacles in the dam break wave path such as man-made or natural obstacles like bridges, trees, and local sills affect flow dynamics, which can lead to the formation of hydraulic jumps and the reflection of the flood wave. Accordingly, the precise prediction of flood parameters such as arrival times, free surface profiles, and flow velocity profiles is essential in order to mitigate flood hazards.
This study aimed to assess the performance of various turbulence models in predicting and estimating dam-break flows and related positive and negative flood wave characteristics over different downstream bed conditions. Three-dimensional (3-D) Computational Fluid Dynamics (CFD) models were created to solve the unsteady Reynolds equations in order to determine the initial stages of the free surface profiles over dry and wet beds and to investigate the generation and propagation of dam-break flows and reflected flood waves in the presence of a bed obstacle. The performance of different Reynolds-averaged Navier-Stokes (RANS) turbulence models has been investigated, and the standard k-ε, RNG k-ε, realizable k-ε, k-ω SST, and v^2-f turbulence models have been studied using OpenFOAM software. Dam-breaks were modelled using the Volume of Fluid (VOF) method employing the Finite Volume Method (FVM).
Both qualitative and quantitative comparisons of numerical simulations with laboratory experiments were completed in order to assess the suitability of different turbulence models. The results of the first study showed that the RNG k-ε model exhibited better performance in capturing the flood wave free surface profiles over both dry- and wet-bed downstream conditions, while from the second study, it was concluded that the k-ω SST model was able to accurately predict the formation and propagation of reflected waves against a bottom obstacle in terms of free surface profiles and negative bore propagation speeds.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/42958 |
| Date | 23 November 2021 |
| Creators | Esmaeeli Mohsenabadi, Saeid |
| Contributors | Nistor, Ioan, Mohammadian, Abdolmajid |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | Attribution 4.0 International, http://creativecommons.org/licenses/by/4.0/ |
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