The Comparison of the Performance of Prandtl| Mixing Length, Turbulence Kinetic Energy, K-e, RNG and LES Turbulence Models in Simulation of the Positive Wave Motion Caused by Dam Break on the Erodible Bed

摘要

Background/Objectives: Dam-break problem study has significant importance in the hydraulic study of the sudden floods. The aim of this research was a prediction of movement pattern of the positive wave. Methods/Statistical Analysis: This research was based on numerical technique of Volume of Fluid (VOF). Flow-3D software was used for simulation. For the first time, the performance of all turbulence models was evaluated in the calculation of free flow surface and bed profiles. Two statistical methods of the regression and relative error were used for determining of accuracy of simulation results. The Spine wine (2005) experimental results were used for validation of numerical simulation. Findings: The results of two statistical methods of regression and normal relative error in comparison between experimental and numerical data showed that the LES turbulence model has the highest efficiency in predicting the free flow surface and sedimentary bed profiles and dimension-less profiles of free surface of the flow, distance- time, velocity-time and acceleration-time of progress of positive wave front. Two last dimensions-less profiles, for the first time were introduced in this research. Based on statistical results the K-e, RNG, Prandtle Mixing Length and Turbulence Kinetic Energy have less efficiency than the LES model, respectively. None of the models were able to predict changes of sedimentary bed appropriately. Therefore, the LES model is most accurate turbulence model in predicting of a positive wave caused by a dam break in mobile bed. The results of this research were compatible with numerical researches on dam-break problem based on VOF technique. Applications: In numerical solving of dam-break hydraulic problem, selection of turbulence model has a significant effect on accuracy of simulation. The VOF technique is fast and powerful method for this purpose.