A new mathematical model for the overtopping against seawalls armored with artificial units in regular waves was established. The 2-D numerical wave flume, based on the Reynolds Averaged Navier-Stokes （RANS） equatio...A new mathematical model for the overtopping against seawalls armored with artificial units in regular waves was established. The 2-D numerical wave flume, based on the Reynolds Averaged Navier-Stokes （RANS） equations and the standard κ-ε turbulence model, was developed to simulate the turbulent flows with the free surface, in which the Volume Of Fluid （VOF） method was used to handle the large deformation of the free surface and the relaxation approach of combined wave generation and absorbing was implemented. In order to consider the effects of energy dissipation due to the armors on a slope seawall, a porous media model was proposed and implemented in the numerical wave flume. A series of physical model experiments were carried out in the same condition of the numerical simulation to determine the drag coefficient in the porous media model in terms of the overtopping discharge. Compared the computational value of overtopping over the seawall with the experimental data, the values of the effective drag coefficient was calibrated for the layers of blocks at different locations along the seawalls.展开更多
利用MIKE21FM模块建立了适用于台州温岭市的高分辨率风暴潮漫滩数值模式,以9711号台风路径为基准,分别以5 km为间隔向两侧平移,构造各种设计台风路径,找到最不利登陆位置进行风暴潮计算,再利用SWAN计算不利路径的堤前台风浪要素,通过经...利用MIKE21FM模块建立了适用于台州温岭市的高分辨率风暴潮漫滩数值模式,以9711号台风路径为基准,分别以5 km为间隔向两侧平移,构造各种设计台风路径,找到最不利登陆位置进行风暴潮计算,再利用SWAN计算不利路径的堤前台风浪要素,通过经验公式计算越浪量,进行溃堤判断。最后将各路径的淹没计算结果取最大包络,画出6档台风的风暴潮淹没范围图。结果表明:在最高等级的915 h Pa时,由于沿海堤防几乎全溃,因此处于沿海平原区的乡镇基本受淹,随台风强度降低淹没水深及范围逐渐减小,最低等级的965 h Pa时无淹没,其他等级风暴潮淹没介于两者之间。展开更多
The flows of nonlinear waves overtopping an obstruction are studied numerically in the present paper. The finite difference method is used to solve the full two dimensional Navier Stokes equations, and the VOF metho...The flows of nonlinear waves overtopping an obstruction are studied numerically in the present paper. The finite difference method is used to solve the full two dimensional Navier Stokes equations, and the VOF method is adopted to deal with free surface deformations. Numerical results of a solitary wave and periodic waves overtopping an rectangular cylinder are obtained respectively. Many complex phenomena, such as water accumulation, wave run up, water jet flows, water jet impact both upon free surface and on a structure, and generation of new waves on the lee side during the process of the waves overtopping an obstacle, can be successfully simulated.展开更多
An empirical formula for estimating the overtopping discharge of wind-waves on a smooth-impermeable-simple slope dyke is derived through model tests in this paper, it can be adopted by related design departments in th...An empirical formula for estimating the overtopping discharge of wind-waves on a smooth-impermeable-simple slope dyke is derived through model tests in this paper, it can be adopted by related design departments in the determination of the crest elevation of the dyke.展开更多
In this paper, the theoretical analysis and experimental studies are employed to investigate the reflection characteristics of partial standing waves caused by wave overtopping and sloping top of structures. Based on ...In this paper, the theoretical analysis and experimental studies are employed to investigate the reflection characteristics of partial standing waves caused by wave overtopping and sloping top of structures. Based on the principle of conservation of wave energy flux, the third-order Stokes wave theory is used to formulate the reflection coefficient at wave overtopping; the calculation results are regressed into an applied expression. A series of experiments of wave reflection for a vertical-wall structure with chamfered and overhanging upper sections are carried out to investigate the influence of top slope on wave reflection. The regularity of variation of wave reflection in this case is analysed based on the experimental results.展开更多
The risk of wind waves in a bay is often overlooked,owing to the belief that peninsulas and islands will inhibit high waves.However,during the passage of a tropical cyclone,a semi-enclosed bay is exposed to twodirecti...The risk of wind waves in a bay is often overlooked,owing to the belief that peninsulas and islands will inhibit high waves.However,during the passage of a tropical cyclone,a semi-enclosed bay is exposed to twodirectional waves:one generated inside the bay and the other propagated from the outer sea.Typhoon Faxai in 2019 resulted in the worst coastal disaster in Tokyo Bay in the last few decades.The authors conducted a post-disaster survey immediately after this typhoon.Numerical modeling was also performed to reveal the mechanisms of unusual high waves.No significant high-wave damage occurred on coasts facing the Pacific Ocean.By contrast,Fukuura-Yokohama,which faces Tokyo Bay,suffered overtopping waves that collapsed seawalls.To precisely reproduce multi-directional waves,the authors developed an extended parametric typhoon model,which was embedded in the JMA mesoscale meteorological model(JMA-MSM).The peak wave height was estimated to be 3.4 m off the coast of Fukuura,in which the contribution of the outer-sea waves was as low as 10%–20%.A fetchlimited wave developed over a short distance in the bay is considered the primary mechanism of the high wave.The maximum wave occurred on the left-hand side of the typhoon track in the bay,which appears to be contrary to the common understanding that it is safer within the semicircle of a storm than on the opposite side.Typhoon Faxai was a small typhoon;however,if the radius was tripled,it is estimated that the wave height would exceed 3 m over the entire bay and surpass 4 m off the coasts of Yokohama and Chiba.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.10572093)the Doctorial Program Foundation of MOE of China(Grant No. 20060248046).
文摘A new mathematical model for the overtopping against seawalls armored with artificial units in regular waves was established. The 2-D numerical wave flume, based on the Reynolds Averaged Navier-Stokes （RANS） equations and the standard κ-ε turbulence model, was developed to simulate the turbulent flows with the free surface, in which the Volume Of Fluid （VOF） method was used to handle the large deformation of the free surface and the relaxation approach of combined wave generation and absorbing was implemented. In order to consider the effects of energy dissipation due to the armors on a slope seawall, a porous media model was proposed and implemented in the numerical wave flume. A series of physical model experiments were carried out in the same condition of the numerical simulation to determine the drag coefficient in the porous media model in terms of the overtopping discharge. Compared the computational value of overtopping over the seawall with the experimental data, the values of the effective drag coefficient was calibrated for the layers of blocks at different locations along the seawalls.
文摘利用MIKE21FM模块建立了适用于台州温岭市的高分辨率风暴潮漫滩数值模式,以9711号台风路径为基准,分别以5 km为间隔向两侧平移,构造各种设计台风路径,找到最不利登陆位置进行风暴潮计算,再利用SWAN计算不利路径的堤前台风浪要素,通过经验公式计算越浪量,进行溃堤判断。最后将各路径的淹没计算结果取最大包络,画出6档台风的风暴潮淹没范围图。结果表明:在最高等级的915 h Pa时,由于沿海堤防几乎全溃,因此处于沿海平原区的乡镇基本受淹,随台风强度降低淹没水深及范围逐渐减小,最低等级的965 h Pa时无淹没,其他等级风暴潮淹没介于两者之间。
文摘The flows of nonlinear waves overtopping an obstruction are studied numerically in the present paper. The finite difference method is used to solve the full two dimensional Navier Stokes equations, and the VOF method is adopted to deal with free surface deformations. Numerical results of a solitary wave and periodic waves overtopping an rectangular cylinder are obtained respectively. Many complex phenomena, such as water accumulation, wave run up, water jet flows, water jet impact both upon free surface and on a structure, and generation of new waves on the lee side during the process of the waves overtopping an obstacle, can be successfully simulated.
文摘An empirical formula for estimating the overtopping discharge of wind-waves on a smooth-impermeable-simple slope dyke is derived through model tests in this paper, it can be adopted by related design departments in the determination of the crest elevation of the dyke.
基金This study is supported by Canadian Hydraulics Center(CHC),R and D Project AMC22000National Natural Science Foundation of China(Grant No.59779004)Foundation of State Key Laboratory of Coastal and Offshore Eng.,Dalian Technology University.
文摘In this paper, the theoretical analysis and experimental studies are employed to investigate the reflection characteristics of partial standing waves caused by wave overtopping and sloping top of structures. Based on the principle of conservation of wave energy flux, the third-order Stokes wave theory is used to formulate the reflection coefficient at wave overtopping; the calculation results are regressed into an applied expression. A series of experiments of wave reflection for a vertical-wall structure with chamfered and overhanging upper sections are carried out to investigate the influence of top slope on wave reflection. The regularity of variation of wave reflection in this case is analysed based on the experimental results.
基金funded by grants awarded to Tokyo Institute of Technology(Japan Society for the Promotion of Science,Nos.16KK0121,19K04964 and 19K24677).
文摘The risk of wind waves in a bay is often overlooked,owing to the belief that peninsulas and islands will inhibit high waves.However,during the passage of a tropical cyclone,a semi-enclosed bay is exposed to twodirectional waves:one generated inside the bay and the other propagated from the outer sea.Typhoon Faxai in 2019 resulted in the worst coastal disaster in Tokyo Bay in the last few decades.The authors conducted a post-disaster survey immediately after this typhoon.Numerical modeling was also performed to reveal the mechanisms of unusual high waves.No significant high-wave damage occurred on coasts facing the Pacific Ocean.By contrast,Fukuura-Yokohama,which faces Tokyo Bay,suffered overtopping waves that collapsed seawalls.To precisely reproduce multi-directional waves,the authors developed an extended parametric typhoon model,which was embedded in the JMA mesoscale meteorological model(JMA-MSM).The peak wave height was estimated to be 3.4 m off the coast of Fukuura,in which the contribution of the outer-sea waves was as low as 10%–20%.A fetchlimited wave developed over a short distance in the bay is considered the primary mechanism of the high wave.The maximum wave occurred on the left-hand side of the typhoon track in the bay,which appears to be contrary to the common understanding that it is safer within the semicircle of a storm than on the opposite side.Typhoon Faxai was a small typhoon;however,if the radius was tripled,it is estimated that the wave height would exceed 3 m over the entire bay and surpass 4 m off the coasts of Yokohama and Chiba.
