## 1 Introduction  
A large natural hazard is posed by dam failure and ensuing potentially catastrophic floods downstream, because of the uncontrolled release of the water [1] stored in the reservoir. To mitigate this impact to the greatest possible degree, it is important to predict the dam-break wave motion by capturing both the temporal and spatial evolutions of floods to manage and reduce the risks caused by flooding [2] and to predict the propagation process effects of the dam-break waves downstream [3]. However, predicting these quantities is challenging, and selecting a suitable model to simulate the movement of the dam-break flood accurately and provide useful information on the flow field is therefore an essential step [4]. The choice of suitable mathematical and numerical models has been shown to be very significant in dam-break flood analyses. Studies on dam-break flows as conducted in analytical solutions began more than one hundred years ago. [PERSON] [5] first derived the earliest analytical solution of the 1D de Saint-Venant equations over a dry bed, [PERSON] [6; 7] and [PERSON] [8] studied wavefronts influenced by frictional resistance,and [PERSON] [9] extended [PERSON]'s solution to the 1D dam-break problem for a wet bed. [PERSON] and [PERSON] [10] applied the methodology developed by [PERSON] [11] for Euler equations of gas dynamics to devise a general procedure for solving the Riemann problem under wet bed conditions. [PERSON] [12] conducted a complete 1D exact Riemann solver to address both wet- and dry-bed conditions. [PERSON] [13] studied the simple analytical solutions for floods originating from sudden dam-breaks using the characteristics method. However, these analytical solutions did not produce accurate results, particularly for wet beds during the initial stages of a dam break [14; 15]. Developments from past studies have provided several numerical models aimed at solving the so-called dam break flooding problem [16], and one-dimensional models, such as Hec-Ras, DAMBRK and MIKE 11, etc. have been used to model dam-break flooding [17]. Two-dimensional (2D) depth-averaged equations have also been widely used to simulate the dam-break flow problem [18; 19; 20; 21; 22], and the results show that shallow water equations (SWE) are suitable for representing fluid flows. However, in some cases, the solutions provided by 2D numerical solvers may not be consistent with the experiments, particularly in the near field [23; 24]. Furthermore, one and two-dimensional models are limited at capturing some details about three-dimensional phenomena [25]. Several three-dimensional (3D) models based on the Reynolds-averaged Navier-Stokes equations (RANS) have been applied to model dam-break flows in an effort to overcome some of the shortcomings of shallow-water models, which were employed to understand the actual behavior of complex flows during the initial stages of a dam break [26; 27; 28] and to study dam-break flows resulting from wave impacts on an obstacle or a bottom sill [19; 29] and turbulent dam-break flow behavior in the near field [4]. Recently, among the commercially available numerical models, the well-known 3D volume of fluid method (VOF)-based CFD modelling software FLOW-3D has been used widely to analyze unsteady free surface flows, due to the increase in computing power brought about by progress in computer technology. This software calculates numerical solutions to RANS equations using a finite-difference approximation, and it also uses the VOF for tracking the free surface [30; 31]; it has been used successfully to model dam-break flows [32; 33]. However, there are certain hydraulic features of dam break flows over space and time that cannot be captured using 2D shallow-water models. The application of full 3D Navier-Stokes equations for real-life field-scale simulations has a higher computational cost [34], and the desired outcomes might not yield more accurate results than the shallow-water model [35].