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In order to meet the needs of marine tourism development, this paper analyzes the water resonance in the inner domain of a fixed floating tourist platform based on a 3D non-hydrostatic model. The tourist platform has a complex structure that is prone to the resonance of the water in the inner domain under wave actions. The water's motion response in the platform's inner domain under wave action is simulated numerically using numerical simulation methods. The non-hydrostatic model used in this paper is based on a semi-implicit method to solve the incompressible Navier–Stokes equations (NSE) and combines the immersed boundary method with the global continuity equations in the pressure zone (the flow zone under the structure) to approach the problem. In this paper, firstly, the resonant frequencies and resonant amplitudes of the water inside the box-shaped ship are calculated and compared with the experimental data to demonstrate the non-hydrostatic model's accuracy in calculating the resonance problem of the water in the inner domain of a fixed floating platform. Secondly, the water's resonant frequencies and resonant modes in the inner domain are calculated by numerical modeling of the floating tourist platform, including rare high-order resonance modes. We found that there are six resonance modes with complex shapes in the water of the inner domain of the tourist platform. Furthermore, the effects of the wall thickness, chord distance and draft of the annular tourist platform on the resonant amplitude values and modes of the water domain within the platform are analyzed in depth. [ABSTRACT FROM AUTHOR]

This paper presents results of a solitary wave propagating over a submerged horizontal plate based on a non-hydrostatic model. A high-resolution advection scheme is employed based on a second-order flux-limiter method. The model is first validated by comparing numerical results with recently obtained measured data. Then, a series of simulations are carried out to investigate the effect of the plate length on the characteristics of vortex shedding and evolution. With the increase in the length of the plate, more dominant vortical structures induced by the solitary wave with the same wave height can be identified near the lee side of the plate. There are two separate positive vortex shedding from the lower corner of the plate near the lee side, which are not presented in experiments. The secondary positive vortex leads to the water surface deformation for the case that is close to the limit when wave breaking occurs. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) non-hydrostatic model is presented for the simulation of dam-break flows. The model solves the Reynolds-averaged Navier–Stokes equations using the projection method. 3D computational grids are constructed from a two-dimensional horizontal unstructured mesh by adding horizontal layers in the vertical direction. Based on the horizontal unstructured grid system, horizontal advection terms are discretized by a momentum conservative scheme. The proposed model is validated with several physical experiments. The agreement between the model results and experimental data is generally good, which demonstrates the capability of the proposed model to resolve dam-break flows over flat and uneven bottoms with complex geometries. Moreover, the efficiency of the model is evaluated with 3D dam-break flow experiments. Comparisons between the non-hydrostatic model and the corresponding quasi-3D shallow water model are also performed, which confirm the role of non-hydrostatic effects in dam-break flows. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) non-hydrostatic model is presented to simulate open-channel free-surface flows involving undular bores. The 3D unsteady mass conservation and momentum equations are solved using an explicit projection method in a nonstandard staggered grid. The grid system is built from a two-dimensional horizontal structured grid by adding horizontal layers. The model is validated using four typical benchmark problems, including undular bore development, an undular bore generated by a sudden discharge, and two test cases involving undular hydraulic jumps. The proposed model results are compared with experimental data and results from other models. Overall, the agreement between the proposed model results and experimental data is generally good, demonstrating the capability of the model to resolve undular bores. In addition, the non-hydrostatic pressure field under the undular free surface is revealed, and the efficiency of the proposed model is presented. It is shown that the proposed model behaves better than a volume of fluid model in terms of efficiency, because the proposed model can use fewer computational grid cells to resolve undular bores in open channels. [ABSTRACT FROM AUTHOR]

Flows in discharge and energy dissipation buildings generally carry a considerable amount of energy. Therefore, it is important to optimize the discharge and energy dissipation to eliminate the redundant energy as much as possible for the safety of the hydro-junction project and the downstream area. In this paper, a smoothed particle hydrodynamics (SPH) model is applied to optimize the discharge and energy dissipation related to hydraulic jumps for a large-scale real hydro-junction project. The capability of the model in resolving hydraulic jumps is validated by comparing the model results with experimental data. Then, the model is applied to optimize the real hydro-junction project, which requires a sizeable computational effort. The optimization is based on comparisons of the velocity field, the location of the jump toe and the energy dissipation rate between two different schemes for the stilling basin. It is found that the two-stage stilling basin is more effective for energy dissipation than the one-stage stilling basin with the same length. Therefore, two-stage energy dissipation should be adopted for discharge and energy dissipation buildings for similar hydro-junction projects. [ABSTRACT FROM AUTHOR]

A hybrid-grid 3D non-hydrostatic model is developed and applied to predict nonlinear regular waves interacting with vertical circular cylinders. The model solves unsteady momentum and mass conservation equations by means of an explicit projection method. The 3D grid system is built from a 2D horizontal grid by adding several horizontal layers. The Perot’s scheme is used to treat horizontal advection terms in momentum equations. The 2D horizontal domain is discretized using a hybrid-grid system comprising rectangular and triangular cells to improve the model boundary-flexibility. The numerical model is validated against the experimental data of Stokes wave and cnoidal wave interacting with a vertical circular cylinder, respectively. Good agreement between model results and the experimental data are achieved, demonstrating the capability of the model on resolving interactions between nonlinear regular waves and vertical circular cylinders. [ABSTRACT FROM PUBLISHER]

A 3D non-hydrostatic model is developed to compute internal waves. A novel grid arrangement is incorporated in the model. This not only ensures the homogenous Dirichlet boundary condition for the non-hydrostatic pressure can be precisely and easily imposed but also renders the model relatively simple in its discretized form. The Perot scheme is employed to discretize horizontal advection terms in the horizontal momentum equations, which is based on staggered grids and has the conservative property. Based on previous water wave models, the main works of the present paper are to (1) utilize a semi-implicit, fractional step algorithm to solve the Navier-Stokes equations (NSE); (2) develop a second-order flux-limiter method satisfying the max-min property; (3) incorporate a density equation, which is solved by a high-resolution finite volume method ensuring mass conservation and max-min property based on a vertical boundary-fitted coordinate system; and (4) validate the developed model by using four tests including two internal seiche waves, lock-exchange flow, and internal solitary wave breaking. Comparisons of numerical results with analytical solutions or experimental data or other model results show reasonably good agreement, demonstrating the model's capability to resolve internal waves relating to complex non-hydrostatic phenomena. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) numerical model based on unstructured grids has been used to study flow and bed evolution in a laboratory meandering channel bend. The model employs the Reynolds-averaged Navier-Stokes equations and the low-Reynolds-number turbulence model for flow simulation. The model incorporates the suspended-load transport module and the bed-load transport module to simulate sediment transport and employs the sediment continuity equation to calculate channel bed evolution. The numerical simulation is performed in a meandering channel with a movable bed, in which the suspended load is comparable to the bed load. The model captures the main features of the bathymetry at equilibrium conditions. The streamwise velocity profiles and the suspended sediment concentration profiles at equilibrium conditions are also predicted by this simulation, and the agreement with the measured data is generally reasonable. The influence of including the suspended load is revealed by the comparison between the results obtained with total-load model and bed-load model in the meandering channel. [ABSTRACT FROM AUTHOR]

The success or failure of river closure is directly related to the construction period and project benefit. Therefore, it is very necessary to study the river closure by an appropriate method. In this paper, a 1D–2D coupled river closure model is established to optimize the closure flow rate, closure period, and layout of a real closure project. The 1D transition model between open channel flow and pressurized flow is established by a finite volume scheme. For the 2D model, 2D shallow water equations are solved using an unstructured finite volume scheme. The 1D model and 2D model are coupled by considering the mass and momentum conservation. To validate the model, a physical experiment of a real river closure project is set up according to the gravity similarity criterion with a scale of 1:80. Then, the experimental data obtained by the calibrated physical experiment is compared with the numerical results. Good agreements are achieved in terms of surface elevation, velocity, and flow rate. Finally, the real river closure project is further investigated by the model. The layout, closure flow rate and closure period of this project is analyzed and optimized. The original design of the berm is more suitable to discharge the flow. Moreover, the first stage cofferdam should be removed to floor elevation upstream and downstream of the dam. The river closure flow rate should not exceed 2380 m3/s. [ABSTRACT FROM AUTHOR]

Characteristics of hydrodynamic forces and flow fields around the semi-submersible platform induced by the internal solitary wave (ISW) propagation were investigated in a 3D numerical wave tank. Good agreements between numerical results and experimental data of forces and torque on the platform were achieved. The hydrodynamic loads increased and decreased with the increases in the ISW amplitude and fluid depth ratio, respectively. The pressure mainly contributed to the force on the platform. The horizontal forces on bracings were negligible. Almost all the vertical forces on the platform were derived from those on pontoons. The horizontal force and torque on the platform increased with the increases in the angle between the platform symmetrical axis and the ISW propagation direction. The platform subjected the maximum vertical force when the angle was 0°. There were obvious velocity reductions around the platform during the ISW propagation, as visible vortexes shedding around the platform could be observed. Complexities of the distributions of flow fields around the platforms located at the 30°- and 60°-direction were greater than those around the platforms located at the 0°- and 90°-direction. Flow fields around the same kind components of each platform located at different angles were similar. [ABSTRACT FROM AUTHOR]