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Xie M.-X.,Tianjin University | Xie M.-X.,Tianjin Research Institute for Water Transport Engineering
Journal of Hydrodynamics | Year: 2012

A process-based 3-D hydrodynamic model is established to simulate the rip current structures under irregular bathymetry. The depth-varying wave-induced residual momentum, the surface rollers, the turbulent mixing and the wave-current interactions are considered. Experimental datasets are used to validate the model, and it is shown that the model can effectively describe the 3-D structures of the rip currents in both normal and oblique wave incident cases. The flow patterns of the rip currents see various characteristics for different incident wave directions. In the normal incident case, pairs of counter-rotating primary circulation cells are formed, and an offshore rip flow occurs in the embayment troughs. The peak seaward velocities occur at the top of the bed boundary layer, and the undertow is incorporated in addition to the rip currents. In the oblique incident case, the longshore currents are dominant, which result in a meandering flow along the depth contour, and the undertow is weaker compared to that in the normal incident condition. © 2012 Publishing House for Journal of Hydrodynamics. Source


Xie M.,Tianjin Research Institute for Water Transport Engineering | Xie M.,Tianjin University
Ocean Modelling | Year: 2011

A three-dimensional numerical model was established to simulate the wave-induced currents. The depth-varying residual momentum, surface roller, wave horizontal and vertical turbulent mixing effects were incorporated as major driving forces. A surface roller evolution model considering the energy transfer, roller density and bottom slope dissipation was developed. The expression of the wave-induced horizontal turbulent mixing coefficient proposed by Larson and Kraus (1991) was extended to three-dimensional form. Plenty of experimental cases were used to validate the established model covering the wave setup, undertow, longshore currents and rip currents. Validation results showed the model could reasonably describe the main characteristics of different wave-induced current phenomena. The incorporation of surface roller for breaking waves should not be neglected in the modeling of surfzone hydrodynamics. The wave-induced turbulent mixing affects the structures of wave-induced current either in horizontal or in vertical directions. Sensitivity analysis of the major calibration parameters in the established model was made and their ranges were evaluated. © 2011 Elsevier Ltd. Source


Lv B.,Tianjin Research Institute for Water Transport Engineering
China Ocean Engineering | Year: 2014

A higher-efficient three-dimensional non-hydrostatic model is developed to simulate small amplitude free surface flows based on a staggered unstructured grid. In this model, a fractional step algorithm is adopted to solve the Navier-Stokes equations in two major steps. A top-layer pressure method is proposed to minimize the number of vertical layers and subsequently the computational cost. Three classical examples of small amplitude free surface flows are used to demonstrate the capability and efficiency of the model. The satisfactory results demonstrated the capability and efficiency of modelling a range of small amplitude free surface flows with only a small number of vertical layers. © 2014, Chinese Ocean Engineering Society and Springer-Verlag Berlin Heidelberg. Source


Xiao H.,Tianjin Research Institute for Water Transport Engineering
Hydraulic Engineering III - Proceedings of the 3rd Technical Conference on Hydraulic Engineering, CHE 2014 | Year: 2015

Based on the measured wave data within one year in Andaman Sea, Myanmar, the wave frequency spectrum and the directional spectrum are calculate by fast Fourier transform method. The frequency spectrum results show that single peak spectrum is given priority to this sea area, the annual average frequency spectrum peak period for 8 s, the wave spectrum energy is biggest in summer, followed by autumn, spring and winter; the directional spectrum results show that the wave energy concentrate angle is between 200°-250°, the main wave direction is southwest. © 2015 Taylor & Francis Group, London, UK. Source


Yan B.,Tianjin Research Institute for Water Transport Engineering
Hydraulic Engineering III - Proceedings of the 3rd Technical Conference on Hydraulic Engineering, CHE 2014 | Year: 2015

The tidal current is one of the most important factors for closure of a cofferdam in port and coastal engineering. A 3d mathematical model was established to help estimate the hydrodynamic environment in the process of closure of a cofferdam in Caofeidian Harbour. It is shown from simulated results that the model is able to reflect the vertical changes of currents around the project reasonable. The characteristic velocities in final closure from the prediction results were analyzed. Some suggestions were also proposed for the closure of the cofferdam. © 2015 Taylor & Francis Group, London, UK. Source

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