Numerical simulation of oscillatory flows over a rippled bed by immersed boundary method |
| |
| Institution: | 1. Tropical Marine Science Institute, National University of Singapore, 18 Kent Ridge Road, Singapore 119227, Singapore;2. Department of Civil and Environmental Engineering, National University of Singapore, No. 1 Engineering Drive 2, Singapore 117576, Singapore;1. College of Harbour, Coastal and Offshore Engineering, Hohai University, Nanjing, China;2. Deltares, Delft, The Netherlands;3. Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands;4. MOE Key Laboratory for Coast and Island Development, Nanjing University, Nanjing, China;5. Nanjing Hydraulic Research Institute, Nanjing, China;6. State Key Laboratory for Estuarine and Coastal Studies, East China Normal University, Shanghai, China;1. Delft University of Technology, Faculty of Civil Engineering and Geosciences, Department of Hydraulic Engineering, Stevinweg 1, 2628 CN Delft, Netherlands;2. Utrecht University, Faculty of Geosciences, Department of Physical Geography, Heidelberglaan 2, 3584 CS, Utrecht, Netherlands |
| |
| Abstract: | In this paper, a well-developed numerical model based on the immersed boundary (IB) method is used to study oscillatory flows over a bed with large-amplitude ripples in a systematic manner. The work shows that the complex flow over the rippled bed can be numerically dealt with in Cartesian coordinate by the IB method and that the IB method is able to provide main features of the flows near the ripples. An accurate simulation of vortices generation as a result of flow separation at the rippled bed is obtained. It is found that the oscillatory flows start to separate during the flow deceleration when the Keulegan–Carpenter (KC) number is small. The steady streaming for various ripple steepness is simulated and the criterion for separating the single and double structure streaming is also discussed. Moreover, a new type of steady streaming which consists of a pair of embedded recirculations in the vicinity of the ripple trough is obtained for relatively steep ripples in this work. The numerical results, including the steady streaming in particular, may be helpful to improve the understanding of the sediment transport and the seabed evolution with natural ripples under sea waves. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
