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781.
782.
High-Order Models of Nonlinear and Dispersive Wave in Water of Varying Depth with Arbitrary Sloping Bottom 总被引:4,自引:0,他引:4
Hong Guangwen
Professor Coastal Ocean Engineering Research Institute Hohai University Nanjing P. R. China. 《中国海洋工程》1997,(3)
High-order models with a dissipative term for nonlinear and dispersive wave in water of va-rying depth with an arbitrary sloping bottom are presented in this article.First,the formal derivations toany high order of μ(=h/λ,depth to deep-water wave length ratio)and ε(=α/h,wave amplitude todepth ratio)for velocity potential,particle velocity vector,pressure and the Boussinesq-type equations forsurface elevation η and horizontal velocity vector U at any given level in water are given.Then,the exactexplicit expressions to the fourth order of μ are derived.Finally,the linear solutions of η,U,C(phase ce-lerity)and C_g(group velocity)for a constant water depth are obtained.Compared with the Airy theory,excellent results can be found even for a water depth as large as the wave legnth.The present high-ordermodels are applicable to nonlinear regular and irregular waves in water of any varying depth(from shal-low to deep)and bottom slope(from mild to steep). 相似文献
783.
利用渤海中部海域泥温实测资料,计算出该海域海底热扩散率及恒温层深度。结果表明,8#平台处的热扩散率为0.001~0.005cm2s-1,A(B)平台处为0.002~0.010cm2s-1。恒温层深度8#平台处为8m,A(B)平台处10m,也有差异。与陆地比较,海底恒温层深度较浅,且水深越深恒温层深度越浅。 相似文献
784.
李文勤 《中国海洋大学学报(自然科学版)》1989,(4)
本文通过对中太平洋北部海盆表层和柱状沉积物中钙质超微化石的分析鉴定,讨论了该调查区处在溶跃面以下表层沉积物中钙质超微化石的种数与水深变化的关系,推测出本调查区中Ⅰ区的碳酸盐补偿深度约5300米。根据地层中出现的标准化石,对柱状岩芯M_(14)进行了地层年代划分。最上部地层年代约为27万年前,向下1米处年代约为44万年前,3.66米处年代约为122万年前。 相似文献
785.
对东海84个表层沉积样品和5个重力柱状样中的翼足类和浮游有孔虫丰度、浮游有孔虫碎壳率和底栖有孔虫群中胶结质类的比例等进行了定量分析,确定了东海现代文石补偿深度(ACD)位于约600 m处,碳酸盐溶跃面在约1 400 m处.末次冰期时随着碳酸盐溶解作用的显著减弱,ACD大幅度下降至现代的1 000 m之下. 相似文献
786.
The height of a wave at the time of its breaking, as well as the depth of water in which it breaks, are the two basic parameters that are required as input in design exercises involving wave breaking. Currently the designers obtain these values with the help of graphical procedures and empirical equations. An alternative to this in the form of a neural network is presented in this paper. The networks were trained by combining the existing deterministic relations with a random component. The trained network was validated with the help of fresh laboratory observations. The validation results confirmed usefulness of the neural network approach for this application. The predicted breaking height and water depth were more accurate than those obtained traditionally through empirical schemes. Introduction of a random component in network training was found to yield better forecasts in some validation cases. 相似文献
787.
在纯间断化地形的条件下,从理论分析和数值计算二方面探讨了亚惯性频率地形波的频散关系。指出正压亚惯性频率地形波的波模直接取决于间断点的个数和间断度。连续地形可以看成是纯间断地形的极限情况,因此,连续地形的起伏程度有类似间断度的作用。在对连续地形的频散关系进行数值计算时,水平步长的选取对计算结果有很大的影响。 相似文献
788.
1 .IntroductionIntheexploitationofoceanresourcesandintheutilizationofoceanspaces,verylargefloatingstructures (VLFS)suchasMega FloatinJapan (Isobe ,1 999)andMobileOffshoreBase (MOB)inUSA (Remmers ,1 999)playasignificantrole .However,owingtotheirlargesizesandrelativelylowbendingrigidities ,theirhydroelasticresponsesinwavesareofthemostconcern .ManystudieshavebeencarriedoutforthepredictionofthehydroelasticresponsesofVLFS′s (Kashiwagi,2 0 0 0 ;Cui,2 0 0 2 ) .However,inalmostallofthesestu… 相似文献
789.
Experimental investigations are carried out on wave-induced pressures and uplift forces on a submarine pipeline (exposed, half buried and fully buried) in clayey soil of different consistency index both in regular and random waves. A study on scour under the pipeline resting on the clay bed is also carried out. It is found that the uplift force can be reduced by about 70%, if the pipeline is just buried in clay soil. The equilibrium scour depth below the pipeline is estimated as 42% of the pipe diameter for consistency index of 0.17 and is 34% of the pipe diameter for consistency index of 0.23. The results of the present investigations are compared with the results on sandy soil by Cheng and Liu (Appl. Ocean Res., 8(1986) 22) to acknowledge the benefit of cohesive soil in reducing the high pore pressure on buried pipeline compared to cohesionless soil. 相似文献
790.
Mixed layer depth front and subduction of low potential vorticity water in an idealized ocean GCM 总被引:4,自引:0,他引:4
It is known that there is a front-like structure at the mixed layer depth (MLD) distribution in the subtropical gyre, which
is called the MLD front, and is associated with the formation region of mode water. In the present article, the generation
mechanism of the MLD front is studied using an idealized ocean general circulation model with no seasonal forcing. First,
it is shown that the MLD front occurs along a curve where u
g
·∇T
s
= 0 is satisfied (u
g
is the upper ocean geostrophic velocity vector, T
s
is the sea surface temperature and ∇ is the horizontal gradient operator). In other words, the front is the boundary between
the subduction region (u
g
·∇T
s
> 0) and the region where subduction does not occur (u
g
·∇T
s
< 0). Second, we have investigated subduction of low potential vorticity water at the MLD front, which has been pointed out
by past studies. Since u
g
·∇T
s
= 0 at the MLD front, the water particles do not cross the outcrop at the MLD front. The water that is subducted at the MLD
front has come from the deep mixed layer region where the sea surface temperature is higher than that at the MLD front. The
temperature of the water in the deep mixed layer region decreases as it is advected eastward, attains its minimum at the MLD
front where u
g
·∇T
s
= 0, and then subducts under the warmer surface layer. Since the deep mixed layer water subducts beneath a thin stratified
surface layer, maintaining its thickness, the mixed layer depth changes abruptly at the subduction location. 相似文献