A comprehensive study on dam-break flow over dry and wet beds

• Published in: Ocean engineering 2019-09, Vol.188, p.106279, Article 106279
• Main Authors: Khoshkonesh, Alireza, Nsom, Blaise, Gohari, Saeed, Banejad, Hossein
• Format: Article
• Language: English
• Subjects: Dam-break; Dry and wet beds; Initial conditions and reservoir geometry; LES; VOF
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2019.106279

This paper presents a comparative study of the influence of the initial and geometrical conditions on dam-break flow. The conditions are including the reservoir still water level, length and width as well as tail-water depth on dry and wet beds, respectively. The free surface evolution is analyzed through the volume of fluid (VOF) method. The sensitivity to mesh resolution and turbulence closure models are evaluated in three cell sizes and four models, respectively. Likewise, the turbulence closure models namely Reynolds averaged Navier-Stokes (RANS) and large eddies simulation (LES) are compared with the previous experimental data. The LES showed relatively better agreement than other ones on the free surface evolution. The results declared the crucial role of the initial and geometrical conditions on the free surface progression, flow energy, outflow and inflow hydrographs and the resultant forces. •The following characteristics are function of initial water level and reservoir geometry•free surface height, advancing distance, the Froude number and the specific energy.•The reservoir outflow hydrograph and depth and tangential and normal forces.•Formation of the vorticities near field in the vicinity of the walls and flow forehead.•The dam break flow hydraulic characteristics over dry bed differs from the wet bed.•Three distinct regions are formed in the dam break over wet bed•The upstream: subcritical flow regime.•The jet body: transitional flow.•The downstream: subcritical flow regime.•The reservoir outflow depth and hydrograph are including three distinct parts•Very initial: rapid release of the reservoir, steep slope of the free surface, the domination of the kinetic energy.•Middle: the approximately constant depth, horizontal flow development more than vertical, balance between kinetic and potential energies.•Last: gradually release of the reservoir, gentle slope of the free surface, the domination of potential energy and viscosity forces.•The optimal performance of the VOF-LES model in prediction the dam-break flow characteristics•The relatively more satisfactory performance of the LES than the RANS models in prediction the dam-break free surface evolution.