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Wave Dissipation Characteristics of A Mountain-Type Breakwater

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China Ocean Engineering 2020年第6期34卷 863-870页

作者： GONG Ye-jun zhan jie-min HU Wen-qing FAN Qing CAI Wen-hao MOE-LCSM School of Mathematics and StatisticsHunan Normal UniversityChangsha 410081China Department of Applied Mechanics and Engineering Sun Yat-sen UniversityGuangzhou 510275China

One mountain-type breakwater consisting of two inclined plates and one vertical plate is proposed based on several types of traditional free surface breakwaters, including the horizontal plate, curtain wall, and trapezoidal barriers. The interaction between the regular waves and the fixed free surface mountain-type breakwater is measured in one wave flume(15.0 m×0.6 m×0.7 m). The wave propagation, reflection, and transmission process are simulated using the VOF method and the hybrid SAS/laminar method. The simulated wave profiles are consistent with the experimental observations. For waves with a length smaller than four times width of the mountain-type breakwater, the reflected wave amplitudes are slightly larger than those of the vertical-plate breakwater, while the wave transmission coefficients are all smaller than 0.5, and the wave loss coefficients are larger than 0.7. The wave energy is dissipated by wave breaking on the windward inclined plate, and turbulent flow around the vertical plate and the leeward inclined plate.

关键词： wave-structure interaction mountain-type breakwater free surface breakwater

NUMERICAL PREDICTION OF PARTICLE MIXING BEHAVIOR IN A BUBBLING FLUIDIZED BED

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Journal of Hydrodynamics 2007年第3期19卷 335-341页

作者： WU Chun-liang zhan jie-min Engineering College Guangdong Ocean University Zhanjiang 524088 China Department of Applied Mechanics and Engineering Zhongshan University Guangzhou 510275 China

In this article the hard-sphere Discrete Particle Model （DPM） is used to study the mixing behavior of particles in the 2-D fluidized bed. Different flow patterns in the bed for two kinds of inlet configurations, namely free bubbling and jet bubbling mode, are captured by the numerical model, under specific superficial gas velocities. To examine the degree of particle mixing, the Fan index is applied. The numerical results show that the rate of particle mixing is larger in the jet bubbling than that in the free bubbling mode. The gross circulations of particles in the jet bubbling bed give a higher degree of mixing because of the involvement of a greater number of particles.

关键词： Discrete Particle Model (DPM) particle mixing fluidized bed

NUMERICAL INVESTIGATION OF FLOW PATTERNS IN DIFFERENT PUMP INTAKE SYSTEMS

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Journal of Hydrodynamics 2012年第6期24卷 873-882页

作者： zhan jie-min WANG Ben-cheng YU Ling-hui LI Yok-sheung TANG Ling Department of Applied Mechanics and Engineering Sun Yat-sen University Department of Civil and Structural Engineering The Hong Kong Polytechnic University

A 3-D numerical model for pump intake is established based on the Navier-Stokes equations with the RNG k-ε turbulence model and the VOF method to simulate the free surface. The applicability of the proposed model is validated by a test case of non-symmetric pump-intake bay. The predicted locations, structures and shapes of all vortices are in good agreement with those observed in experiments, though with some differences in vorticity strengths. The flow pattern and the efficiency of five types of pump intake systems are studied. The discharge and the velocity tmiformity of the intake system are used as indices to evaluate its performance.

关键词： pump intake Navier-Stokes equations VOF method

CHEBYSHEV FINITE SPECTRAL METHOD FOR 2-D EXTENDED BOUSSINESQ EQUATIONS

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Journal of Hydrodynamics 2011年第1期23卷 1-11页

作者： LI Yok-sheung zhan jie-min, SU Wei Department of Civil and Structural Engineering The Hong Kong Polytechnic University Hong Kong China Department of Applied Mechanics and Engineering Sun Yat-sen University Guangzhou 510275 China

In this article,an accurate Chebyshev finite spectral method for the 2-D extended Boussinesq equations is *** method combines the advantages of both the finite difference and spectral *** Adams-Bashforth predictor and the fourth-order Adams-Moulton corrector are adopted for the numerical solution of the governing differential *** efficient wave absorption strategy is also proposed to effectively absorb waves at outgoing wave boundaries and reflected waves from the interior of the computational domain due to barriers and bottom slopes at the incident wave boundary to avoid contamination of the specified incident wave *** proposed method is verified by a case where experimental data are available for comparison for both regular and irregular *** case is wave diffraction over a shoal reported by Vincent and *** results agree very well with the corresponding experimental data.

关键词： Chebyshev polynomial finite spectral method irregular waves

A LARGE EDDY SIMULATION TURBULENCE MODEL FOR COASTAL SEAS AND SHALLOW WATER PROBLEMS

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Journal of Hydrodynamics 2001年第4期13卷 24-27页

作者： zhan, jie-min Li, Yok-Sheung Dept. of Appl. Mech. and Eng. Zhongshan Univ. Guangzhou 510275 China

In large scale motions of circulations in coastal seas and shallow-water problems, different characteristics of flow in the horizontal plane and in the vertical direction are expected. A new large eddy simulation model was proposed. There are some differences between the present method and the other LES models. The philosophy of the large eddy simulation and the directional eddy viscosity method were applied in the horizontal plane and in the vertical direction, respectively. Compared with the other LES models in which there is no difference between horizontal viscosity and vertical viscosity, the proposed method is reasonable.

关键词： Computational fluid dynamics Computer simulation

TYPHOON PROCESS AND ITS IMPACT ON THE SURFACE CIRCULATION IN THE NORTHERN SOUTH CHINA SEA

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Journal of Hydrodynamics 2011年第1期23卷 95-104页

作者： TANG Ling zhan jie-min CHEN Yi-zhan LI Yok-sheung NIE Yu-hua Department of Applied Mechanics and Engineering Sun Yat-sen University Guangzhou 510275 China Department of Civil and Structural Engineering The Hong Kong Polytechnic University Hong Kong China South China Sea Branch State Oceanic Administration Guangzhou 510300 China

A severe typhoon Utor,occurring between July 3 and 8,2001,brought heavy rainfall,strong wind and storm *** was responsible for tremendous destruction and economic losses in Philippines,Taiwan and *** air-sea model system （MM5 and Princeton Ocean Model（POM））was built to simulate meteorological dynamics and ocean circulation in the South China Sea（SCS）.In the POM the output of MM5 was used as the input *** an increased number of vertical levels,a high-resolution planetary boundary layer scheme and updated landuse/vegetation data,the accuracy of computing wind,temperature and other meteorological fields are improved in near surface and upper levels in MM5 *** simulated trajectory and wind speed of Utor are close to the observed *** simulated distribution of rainfall is accorded well with measured data in the Pearl River Delta（PRD）*** different meteorological stations in Hong Kong,the wind,temperature and sea surface pressure are well *** simulated ocean surface current and surface temperature fields have an obvious rightward-biased response to the typhoon Utor,and the maximum velocity and the lowest temperature region appear in the 30 km of the right side of the typhoon *** typhoon Utor could make the water 50m under the surface ocean unwell to surface and the ocean surface temperature decrease by about 2°C.

关键词： mesoscale model MM5 Princeton Ocean Model(POM) air-sea coupling ocean surface circulation

IMPROVED DEM-CFD MODEL AND VALIDATION:A CONICAL-BASE SPOUTED BED SIMULATION STUDY

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Journal of Hydrodynamics 2010年第3期22卷 351-359页

作者： RONG Liang-wan zhan jie-min Department of Applied Mechanics and Engineering Sun Yat-sen University Guangzhou 510275 China Department of Applied Mechanics and Engineering Sun Yat-sen University Guangzhou 510275 China Guangdong Province Key Laboratory of Coastal Ocean Engineering Sun Yat-sen University Guangzhou 510275China

An improved and efficient DEM-CFD approach is developed for spouted beds. A nonlinear Discrete Element Method （DEM）, with a concept of spring, dash-pot and friction slider, is used for tracing the movement of each individual particle. The gas flow is described by a set of reorganized governing equations. Two phases are coupled through contributions due to effects of porosity, viscosity and drag. All equations are solved with the commercial package Fluent with an implementation of User Defined Functions （UDF）. To validate the improved model, a two-dimensional conical-base spouted bed is chosen as a case study. An unstructured mesh system is adopted instead of regular grid system. The simulation also takes the Saffman force and Magnus effect into account. The calculation results show good agreement with the experimental observations which are taken from the literature.

关键词： Discrete Element Method (DEM) spouted bed Fluent User Defined Functions (UDF) unstructured mesh

A study of the effect of local scour on the flow field near the spur dike

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Theoretical & Applied Mechanics Letters 2024年第2期14卷 98-105页

作者： Yu-Tian Li jie-min zhan Wing-Hong Onyx Wai Department of Industrial Design School of Industrial Design and Ceramic ArtFoshan UniversityFoshan 528000China Department of Applied Mechanics and Engineering Shenzhen Campus of Sun Yat-sen UniversityShenzhen 518107China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China

The flow field near a spur dike such as down flow and horseshoe vortex system(HVS)are susceptible to the topographic changes in the local scouring process,resulting in variation of the sediment transport with *** this study,large eddy simulations with fixed-bed at different scouring stages were conducted to investigate the changes in flow *** results imply that the bed deformation leads to an increase in flow rate per unit area,which represent the capability of sediment transportation by water,in the scour ***,the intensity of turbulent kinetic energy and bimodal motion near the sand bed induced by the HVS were also ***,the peak moments between the two sediment transport mechanisms were ***,understanding the complex feedback mechanism between topography and flow field is essential for the local scour problem.

关键词： Spur dike Local scour Large eddy simulation Down flow Horseshoe vortex system

Responses of thermal structure and vertical dynamic structure of South China Sea to Typhoon Chanchu

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Journal of Hydrodynamics 2014年第3期26卷 458-466页

作者：陈宜展詹杰民罗莹莹韦永康唐灵 Department of Applied Mechanics and Engineering Sun Yat-sen University Department of Civil and Environmental Engineering The Hong Kong Polytechnic University

The response of the South China Sea（SCS） to Typhoon Chanchu（2006） was examined using the MM5 and POM model. In the POM model, sea surface boundary conditions were forced by the simulation wind field from MM5, the velocity forcing was introduced in the eastern boundary and the computational schemes of heat fluxes at the surface were introduced. Comparison with the observation data shows that the simulated results are reliable. In the response process of the SCS to Typhoon Chanchu, the influence of the heat fluxes on thermal structure of the SCS was regionally different. Strong wind forcing would lead to upwelling phenomenon in the lateral boundary of deep water basin. Furthermore, the Ekman pumping theory was used to discuss subsurface upwelling and downwelling phenomenon in typhoon forced stage.

关键词： South China Sea(SCS) typhoon thermal structure vertical dynamic structure Mesoscale Model 5(MM5) princeton ocean model(POM)