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Water Science & Technology Vol 66 No 5 pp 909–917 © IWA Publishing 2012 doi:10.2166/wst.2012.213

Numerical simulation of undular jumps on graveled bed using volume of fluid method

Fatemeh Rostami, Saeed Reza Sabbagh Yazdi, Md Azlin Md Said and Mahdi Shahrokhi

School of Civil Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Seberang Perai Selatan, P. Penang, Malaysia E-mail: azlin@eng.usm.my
K.N. Toosi University of Technology, Tehran, Iran


ABSTRACT

Undular hydraulic jumps are characterized by a smooth rise of the free surface, followed by a train of stationary waves. These jumps sometimes occur in natural waterways and rivers. Numerical difficulties are especially distinct when the flow condition is close to the critical value because of the high sensitivity of the near-critical flow field to flow and channel conditions. Furthermore, the free surface has a wavy shape, which may indicate the occurrence of several transitions from supercritical to subcritical states and vice versa (i.e., undular hydraulic jumps). In this study, a flow model is used to predict an undular hydraulic jump in a rectangular open channel. The model is based on the general two-dimensional, Reynolds-averaged, Navier–Stokes flow equations. The resulting set of partial differential equations is solved using the FLOW-3D solver. The results are compared with the experimental data to validate the model. The comparative analysis shows that the proposed model yields good results. Several types of undular hydraulic jumps occurring in different situations are then simulated to prove the potential application of the model.

Keywords: bed roughness; free surface modeling; turbulent flow; undular hydraulic jump; VOF method


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