scholarly journals Numerical Analysis of Vertical Breakwater Stability under Extreme Waves

2020 ◽  
Vol 8 (12) ◽  
pp. 986
Author(s):  
Meng-Syue Li ◽  
Cheng-Jung Hsu ◽  
Hung-Chu Hsu ◽  
Li-Hung Tsai
Keyword(s):  
Numerical Model ◽  
Stokes Equations ◽  
Rear Side ◽  
Phase Lag ◽  
Back Side ◽  
Extreme Waves ◽  
Wave Overtopping ◽  
Overturning Stability ◽  
Vertical Breakwater ◽  
Caisson Breakwater

The purpose of this study is to perform a numerical simulation of caisson breakwater stability concerning the effect of wave overtopping under extreme waves. A numerical model, which solves two-dimensional Reynolds-averaged Navier–Stokes equations with the k−ε turbulence closure and uses the volume of fluid method for surface capturing, is validated with the laboratory observations. The numerical model is shown to accurately predict the measured free-surface profiles and the wave pressures around a caisson breakwater. Considering the dynamic loading on caisson breakwaters during overtopping waves, not only landward force and lift force but also the seaward force are calculated. Model results suggest that the forces induced by the wave overtopping on the back side of vertical breakwater and the phase lag of surface elevations have to be considered for calculating the breakwater stability. The numerical results also show that the failure of sliding is more dangerous than the failure of overturning in the vertical breakwater. Under extreme waves with more than 100 year return period, the caisson breakwater is sliding unstable, whereas it is safe in overturning stability. The influence of wave overtopping on the stability analysis is dominated by the force on the rear side of the caisson and the phase difference on the two ends of caisson. For the case of extreme conditions, if the impulse force happens at the moment of the minimum of load in the rear side, the safety factor might decrease significantly and the failure of sliding might cause breakwater damage. This paper demonstrates the potential stability failure of coastal structures under extreme sea states and provides adapted formulations of safety factors in dynamic form to involve the influence of overtopping waves.

Numerical Simulation of Wave Overtopping of Breakwater Armored with Porous Layers and Water-Structure Impaction

2012 ◽  
Vol 226-228 ◽  
pp. 1255-1259
Author(s):  
Zong Liu Huang ◽  
Peng Zhi Lin
Keyword(s):  
Porous Media ◽  
Numerical Model ◽  
Wave Height ◽  
Stokes Equations ◽  
Water Structure ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Wave Overtopping ◽  
Impact Forces ◽  
The Impact

A numerical model has been developed to study wave overtopping of permeable units protected breakwater and water-structure impactions. The numerical model solves the Reynolds Averaged Navier-Stokes equations outside of porous media and solves the spatially averaged Navier-Stokes equations in porous media, respectively. The numerical model is first validated by experimental data. The validated model is then employed to investigate the breaking wave overtopping porous media protected breakwater. The overtopping discharge and impact forces on the structures behind the crown wall in different wave conditions are studied. The increase of wave height brings increasing maximum overtopping discharges and different spatial distribution of water behind the crown wall. The impact forces on the structures are determined by both incident wave height and relative positions of the structures.

scholarly journals Experimental and Numerical Study on Water Filling and Air Expelling Process in a Pipe with Multiple Air Valves under Water Slow Filling Condition

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2511
Author(s):  
Jintao Liu ◽  
Di Xu ◽  
Shaohui Zhang ◽  
Meijian Bai
Keyword(s):  
Numerical Model ◽  
Stokes Equations ◽  
Numerical Study ◽  
Practical Method ◽  
Navier Stokes ◽  
Physical Processes ◽  
Two Phase ◽  
Saint Venant Equations ◽  
Water Filling ◽  
Air Valve

This paper investigates the physical processes involved in the water filling and air expelling process of a pipe with multiple air valves under water slow filling condition, and develops a fully coupledwater–air two-phase stratified numerical model for simulating the process. In this model, the Saint-Venant equations and the Vertical Average Navier–Stokes equations (VANS) are respectively applied to describe the water and air in pipe, and the air valve model is introduced into the VANS equations of air as the source term. The finite-volume method and implicit dual time-stepping method (IDTS) with two-order accuracy are simultaneously used to solve this numerical model to realize the full coupling between water and air movement. Then, the model is validated by using the experimental data of the pressure evolution in pipe and the air velocity evolution of air valves, which respectively characterize the water filling and air expelling process. The results show that the model performs well in capturing the physical processes, and a reasonable agreement is obtained between numerical and experimental results. This agreement demonstrates that the proposed model in this paper offers a practical method for simulating water filling and air expelling process in a pipe with multiple air valves under water slow filling condition.

Fluid-Structure Interaction Approach for Numerical Investigation of a Flexible Hydrofoil Deformations in Turbulent Fluid Flow

2018 ◽  
Author(s):  
M. Benaouicha ◽  
S. Guillou ◽  
A. Santa Cruz ◽  
H. Trigui
Keyword(s):  
Fluid Flow ◽  
Numerical Model ◽  
Stokes Equations ◽  
Fluid Structure Interaction ◽  
Time Step ◽  
Fluid Structure ◽  
Turbulent Fluid Flow ◽  
Turbulent Fluid ◽  
Structure Interaction ◽  
Ale Formulation

The study deals with a 3D Fluid-Structure Interaction (FSI) numerical model of a rectangular cantilevered flexible hydrofoil subjected to a turbulent fluid flow regime. The structural response and dynamic deformations are studied by analyzing the oscillations frequencies and amplitudes, under a hydrodynamics loads. The obtained numerical results are confronted with experimental ones, for validation. The numerical model is performed in the same geometric, physical and material conditions as the experimental set-up carried out in a hydrodynamic tunnel. A polyacetal (POM) flexible hydrofoil NACA0015 with an angle of attack of 8° is considered to be immersed in a fluid flow at a Reynold number of 3 × 105. The structure is initially at rest and then moved by the action of the fluid flow. The numerical model is based on a strong coupling procedure for solving the Fluid-Structure Interaction problem. The Arbitrary Lagrangian-Eulerian (ALE) formulation of the Navier-Stokes equations is used and an anisotropic diffusion equation is solved to compute the fluid mesh velocity and position at each time step. The finite volume method is used for the numerical resolution of the fluid dynamics equations. The structure deformations are described by the linear elasticity equation which is solved by the finite elements method. The Fluid-Structure coupled problem is solved by using the partitioned FSI implicit algorithm. A good agreement between numerical and experimental results for the hydrodynamics coefficients and hydrofoil deformations, maximum deflection and frequencies is obtained. The added mass and damping are analyzed and then the FSI effect on the dynamic deformations of the structure is highlighted.

scholarly journals APPLICATION OF SMOOTHED PARTICLE HYDRODYNAMICS IN EVALUATING THE PERFORMANCE OF COASTAL RETROFIT STRUCTURES

2018 ◽  
pp. 109 ◽  
Author(s):  
Soroush Abolfathi ◽  
Dong Shudi ◽  
Sina Borzooei ◽  
Abbas Yeganeh-Bakhtiari ◽  
Jonathan Pearson
Keyword(s):  
Numerical Model ◽  
Smoothed Particle Hydrodynamics ◽  
Vertical Wall ◽  
Laboratory Data ◽  
Wave Structure ◽  
Base Case ◽  
Submerged Breakwater ◽  
Wave Overtopping ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

This study develops an accurate numerical tool for investigating optimal retrofit configurations in order to minimize wave overtopping from a vertical seawall due to extreme climatic events and under changing climate. A weakly compressible smoothed particle hydrodynamics (WCSPH) model is developed to simulate the wave-structure interactions for coastal retrofit structures in front of a vertical seawall. A range of possible physical configurations of coastal retrofits including re-curve wall and submerged breakwater are modelled with the numerical model to understand their performance under different wave and structural conditions. The numerical model is successfully validated against laboratory data collected in 2D wave flume at Warwick Water Laboratory. The findings of numerical modelling are in good agreement with the laboratory data. The results indicate that recurve wall is more effective in mitigating wave overtopping and provides more resilience to coastal flooding in comparison to base-case (plain vertical wall) and submerged breakwater retrofit.

Wave Overtopping Plunging on the Rear Side of Composite Breakwater

2021 ◽  
Vol 114 (sp1) ◽  
Author(s):  
Made Narayana Adibhusana ◽  
Jong-In Lee ◽  
Yonguk Ryu
Keyword(s):  
Rear Side ◽  
Wave Overtopping

scholarly journals Experimental and Simulation Study on Validating a Numerical Model for CO2 Density-Driven Dissolution in Water

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 738
Author(s):  
Holger Class ◽  
Kilian Weishaupt ◽  
Oliver Trötschler
Keyword(s):  
Carbon Dioxide ◽  
Numerical Model ◽  
Stokes Equations ◽  
Onset Time ◽  
Navier Stokes ◽  
Grid Refinement ◽  
Navier Stokes Equations ◽  
Laboratory Flume ◽  
Diffusive Processes ◽  
Color Indicator

Carbon dioxide density-driven dissolution in a water-filled laboratory flume of the dimensions 60 cm length, 40 cm height, 1 cm thickness, was visualized using a pH-sensitive color indicator. We focus on atmospheric pressure conditions, like in caves where CO2 concentrations are typically higher. Varying concentrations of carbon dioxide were applied as boundary conditions at the top of the experimental setup, leading to the onset of convective fingering at differing times. The data were used to validate a numerical model implemented in the numerical simulator DuMux. The model solves the Navier–Stokes equations for density-induced water flow with concentration-dependent fluid density and a transport equation, including advective and diffusive processes for the carbon dioxide dissolved in water. The model was run in 2D, 3D, and pseudo-3D on two different grids. Without any calibration or fitting of parameters, the results of the comparison between experiment and simulation show satisfactory agreement with respect to the onset time of convective fingering, and the number and the dynamics of the fingers. Grid refinement matters, in particular, in the uppermost part where fingers develop. The 2D simulations consistently overestimated the fingering dynamics. This successful validation of the model is the prerequisite for employing it in situations with background flow and for a future study of karstification mechanisms related to CO2-induced fingering in caves.

scholarly journals A numerical geotechnical model for computing soil slides at banks of water reservoirs

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nils Reidar B. Olsen ◽  
Stefan Haun
Keyword(s):  
Numerical Model ◽  
Water Level ◽  
Stokes Equations ◽  
Limit Equilibrium ◽  
Three Dimensional ◽  
Field Measurements ◽  
Navier Stokes ◽  
Adaptive Grids ◽  
Groundwater Levels ◽  
Before And After

AbstractSoil slides can occur when the water level in a lake or a reservoir is lowered. This may take place in situations when a reservoir is flushed to remove sediments. The current study describes a three-dimensional numerical model used for the simulation of reservoir flushing that includes the slide movements. The geotechnical failure algorithms start with modelling the groundwater levels at the banks of the reservoir. A limit equilibrium approach is further used to find the location of the slides. The actual movement of the sediments is computed by assuming the soil to be a viscous liquid and by solving the Navier–Stokes equations. The resulting bed elevation changes from the slides are computed in adaptive grids that change as a function of water level, bed erosion and slide movements. The numerical model is tested on the Bodendorf reservoir in Austria, where field measurements are available of the bank elevations before and after a flushing operation. The results from the numerical simulations are compared with these observations. A parameter test shows that the results are very sensitive to the cohesion and less sensitive to the E and G modules of the soil.

Numerical Modelling of Circulation in Lake Sperillen, Norway

2000 ◽  
Vol 31 (1) ◽  
pp. 57-72 ◽  
Author(s):  
N. R. B. Olsen ◽  
D. K. Lysne
Keyword(s):  
Numerical Model ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Field Measurements ◽  
Navier Stokes ◽  
Water Current ◽  
Simple Method ◽  
Vertical Temperature Profile ◽  
Navier Stokes Equations ◽  
Good Agreement

A three-dimensional numerical model was used to model water circulation and spatial variation of temperature in Lake Sperillen in Norway. A winter situation was simulated, with thermal stratification and ice cover. The numerical model solved the Navier-Stokes equations on a 3D unstructured non-orthogonal grid with hexahedral cells. The SIMPLE method was used for the pressure coupling and the k-ε model was used to model turbulence, with a modification for density stratification due to the vertical temperature profile. The results were compared with field measurements of the temperature in the lake, indicating the location of the water current. Reasonably good agreement was found.

scholarly journals Efficient and Accurate 3-D Numerical Modelling of Landslide Tsunami

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2033 ◽  
Author(s):  
Guodong Li ◽  
Guoding Chen ◽  
Pengfeng Li ◽  
Haixiao Jing
Keyword(s):  
Numerical Model ◽  
Mesh Generation ◽  
Water Waves ◽  
High Speed ◽  
Stokes Equations ◽  
Computational Cost ◽  
Similarity Criterion ◽  
Numerical Results ◽  
Mesh Resolution ◽  
Landslide Tsunami

High-speed and accurate simulations of landslide-generated tsunamis are of great importance for the understanding of generation and propagation of water waves and for prediction of these natural disasters. A three-dimensional numerical model, based on Reynolds-averaged Navier–Stokes equations, is developed to simulate the landslide-generated tsunami. Available experiment data is used to validate the numerical model and to investigate the scale effect of numerical model according to the Froude similarity criterion. Based on grid convergence index (GCI) analysis, fourteen cases are arranged to study the sensitivity of numerical results to mesh resolution. Results show that numerical results are more sensitive to mesh resolution in near field than that in the propagation field. Nonuniform meshes can be used to balance the computational efficiency and accuracy. A mesh generation strategy is proposed and validated, achieving an accurate prediction and nearly 22 times reduction of computational cost. Further, this strategy of mesh generation is applied to simulate the Laxiwa Reservoir landslide tsunami. The results of this study provide an important guide for the establishment of a numerical model of the real-world problem of landslide tsunami.

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