流—流耦合效应对南海北部风暴潮影响的数值模拟研究

发布时间：2018-03-07 08:24

本文选题：南海北部区域　切入点：台风风暴潮　出处：《中国科学院研究生院(海洋研究所)》2016年博士论文　论文类型：学位论文

【摘要】：中国南海北部区域受台风及风暴潮灾害影响严重,每年会由台风风暴潮灾害而出现重大经济损失和人员伤亡。在台风等极端天气条件下近岸海浪会对流场和水位的产生极大影响,同时局地流场与水位也会影响到海浪场。因此,在研究台风过程中风暴潮增水与流场演变时,考虑浪-流耦合作用,引入环流模式与海浪模式耦合运算,能得到更准确的模拟结果。目前,浪-流耦合机制的研究还并不成熟,模拟台风风暴潮时,三维模式中浪-流耦合效应对波致增/减水及波致流场影响机理有待进一步验证。在浪-流耦合研究中,浪致流效应中的守恒效应,即辐射应力(或涡度力)效应是一个重要的物理机制,它反映了波浪运动产生的剩余动量通量,另外,波浪破碎引起的湍流效应及浪致底应力/表层应力等非守恒效应对于水位与环流场都有影响。为了研究采用辐射应力(涡度力)以及非守恒效应对波生流及波致增/减水的影响,本文采用了COAWST(Coupled ocean-atmosphere-wave-sediment transport modeling system)浪-流耦合模式中辐射应力方案(Mellor,2008)及涡度力方案(McWilliams等,2004),模拟分析了“黑格比”及”鹦鹉”台风过程中,海浪通过守恒性浪致流效应(辐射应力/涡度力)及非守恒性浪致流效应(表层/底层海浪摩擦,深度引起的海浪破碎等)对风暴潮的影响程度及机制,研究发现:(1)引入浪-流耦合方案后,模拟误差减少了近10%,模拟效果更好,在浪致流效应的影响下,台风中心右侧的增水增加,左侧的减水增强,涡度力方案在近岸区域波致增/减水效果更为明显,使风暴潮强度变化为15%左右,辐射应力方案对陆坡内浅水区更为敏感;(2)相对于守恒性浪致流效应,非守恒性浪致流效应对近岸流场及水位影响较弱,其引起波致增水/减水仅占守恒性波致增水/减水的20%左右,但是其强化了台风中心右侧的增水及向岸流,加强了左侧的减水及离岸流,而在考虑运算效率的前提下,仅采用单向VF守恒性耦合方案能极大提升运算效率,并满足模拟精度要求;(3)涡度力耦合方案对不同路径、移速台风及在不同水深条件下,都能敏感的反映出风暴潮过程及浪-流耦合效应对流场、水位的影响,而对快速移动的台风及在水深较浅情况下,近岸浪致流效应越强,其引发的浪致增水对风暴潮增水贡献越大;(4)COAWST模式台风风暴潮漫滩模拟实验能反应出风暴潮增水及漫滩过程的基本特征,模拟误差控制在20%之内,有较好的模拟精度。
[Abstract]:The northern region of the South China Sea is seriously affected by typhoons and storm surges. In extreme weather conditions such as typhoons and other extreme weather conditions, the near shore waves will have a great impact on the convection field and the water level, and the local flow field and water level will also affect the wave field. In studying the evolution of storm surge and current field during typhoon, considering the wave-current coupling, the coupling operation of circulation model and wave model can be introduced to obtain more accurate simulation results. At present, the study of wave-current coupling mechanism is not yet mature. In the simulation of typhoon storm surge, the effect mechanism of wave-current coupling effect on wave-induced increase / reduction and wave-induced flow field in 3-D model needs to be further verified. In the wave-current coupling study, the conservation effect of wave-induced flow effect is discussed. That is, the radiation stress (or vorticity force) effect is an important physical mechanism, which reflects the residual momentum flux generated by wave motion. In order to study the effects of radiation stress (vorticity force) and non-conservation effect on wave-induced flow and wave-induced flow, the turbulent effect caused by wave breakage and non-conserved effects such as wave bottom stress / surface stress have influence on water level and circulation field in order to study the effects of radiation stress (vorticity force) and non-conservation effect on wave-induced flow. Effects of increased / reduced water, In this paper, the radiation stress scheme in the COAWST(Coupled ocean-atmosphere-wave-sediment transport modeling system model (Mellorne 2008) and the vorticity force scheme (McWilliams et al. 2004) are used to simulate and analyze the typhoon process of "Hegbyb" and "Parrot". The influence degree and mechanism of wave flow effect (radiation stress / vorticity force) and non-conserved wave effect (surface / bottom wave friction, depth induced wave breakage, etc.) on storm surge through conserved wave flow effect (radiation stress / vorticity force), It is found that after introducing the wave-current coupling scheme, the simulation error is reduced by nearly 10%, and the simulation effect is better. Under the influence of the wave induced flow effect, the water increase on the right side of the typhoon center and the water reduction on the left side are increased. The vorticity force scheme is more effective in increasing / reducing water caused by wave in the coastal area, which makes the intensity of storm surge change to about 15%, and the radiation stress scheme is more sensitive to shallow water in the slope than that of conserved wave. The effect of non-conserved wave-induced flow on the inshore flow field and water level is weak, and the wave-induced water increase / water reduction only accounts for about 20% of the conserved wave-induced water increase / water reduction effect, but it strengthens the water increase and directional flow on the right side of the typhoon center. The water reduction and offshore flow on the left side are strengthened, and the unidirectional VF conservation coupling scheme can greatly improve the operation efficiency and satisfy the requirement of simulation accuracy, and the vorticity force coupling scheme can greatly improve the operation efficiency under the premise of considering the operational efficiency, and the vorticity force coupling scheme is applied to different paths. Both the moving typhoon and the typhoon with different water depth can sensitively reflect the storm surge process, the coupled effect of wave and current, the influence of water level, and the stronger the effect on the fast-moving typhoon and the shallow water depth, the stronger the effect of near-shore wave is. The simulation experiment of Typhoon storm surge floodplain can reflect the basic characteristics of storm surge water increasing and floodplain process. The simulation error is controlled within 20%, and the simulation accuracy is better.
【学位授予单位】：中国科学院研究生院(海洋研究所)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P731.23

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