内潮动力机制的数值研究

结合南沙群岛海域出现的内潮现象 ,利用一个两层数值模式 ,通过数值试验来探讨潮汐性质、水体的层结程度、跃层所在的深度、风应力等因子对陆架坡折处内潮特性的影响 ,结果表明 :内潮的波动周期只与海区的潮汐性质有关 ;风应力、非线性效应以及正压潮源地的深度等都可改变内潮的波动振幅 ;内潮的波动振幅随海区的水体层结程度及温跃层所在的深度不同而改变     

两层流体中矩形箱浮体的附加质量和阻尼系数

研究了两层流体中矩形箱浮体的辐射问题。基于特征函数匹配理论,针对矩形箱浮体的三种振荡运动模式(横荡、垂荡和横摇),建立两层流体中矩形箱浮体辐射势的求解方法,导出矩形箱浮体附加质量和阻尼系数的计算公式。对所建立的求解模型进行了数值计算分析,结果表明在矩形箱浮体的某个振荡频率范围内,流体的分层效应对其附加质量和阻尼系数有显著影响的。     

On hydraulic falls of two-layer flow

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Path Transition of the Kuroshio Due to Mesoscale Eddies: A Two-Layer, Wind-Driven Experiment

We have executed numerical experiments using a two-layer, wind-driven ocean model with simplified coastal geometry and bottom topography to investigate the possibility of the Kuroshio path transition due to mesoscale eddies. A straight path easily changes into a meandering path due to the eddy action. For this transition, an anticyclonic eddy is preferable to a cyclonic one when imposed in the beginning region of the Kuroshio (east of Taiwan). When imposed southeast of Kyushu, on the other hand, a cyclonic eddy is more effective than an anticyclonic one. The reverse transition, from a meandering to a straight path, did not occur at all in this experiment. This revised version was published online in August 2006 with corrections to the Cover Date.     

局地凝结加热对大气赤道波动稳定性的影响(英文)

利用β平面上大气斜压强迫模式,探讨了局地海表温度异常所造成的非绝热加热影响的赤道小振幅“拦截波”的稳定性。指出当加热函数是半余弦形式时,在加热区大气的反应是局地性的,但这个加热函数的小扰动能产生非局地性的大尺度反应。平均海表温度降低了赤道波动的稳定性。当稍超过临界值时,小尺度海表温度异常有可能使波动不稳定。     

The baroclinic circulation structure of Yellow Sea Cold Water Mass

The Yellow Sea is a semi-enclosed shallow sea with a deep trough of about 80 m. On the hy-drographic condition in the Yellow Sea, Lie[1] pointed out that it is strongly associated with winter cooling and summer heating, fresh input from rivers into the co…     

厚层近海回填抛石填土层钻孔灌注桩施工技术

烟台港万华工业园码头工程改造项目,设计采用φ600、1000 mm的钻孔灌注桩。上部为厚层近海回填抛石填土层,钻进困难,极易塌孔,成孔难度大,采用大型旋挖钻机带护筒跟管钻进成孔,内外二层套管护壁,穿过回填层及混砂层后,采用泥浆护壁旋挖钻机继续钻进,护筒不再跟进,既可保证成孔质量又能降低施工成本。外护筒可在灌注完成后拔出,重复利用,减少工程造价。     

Influence of the earth rotation on the interfacial wave solutions and wave-induced tangential stress in a two-layer fluid system

Interfacial waves and wave-induced tangential stress are studied for geostrophic small amplitude waves of two-layer .uid with a top free surface and a .at bottom. The solutions were deduced from the general form of linear .uid dynamic equations of two-layer .uid under the f -plane approximation, and wave-induced tangential stress were estimated based on the solutions obtained. As expected, the solutions derived from the present work include as special cases those obtained by Sun et al. (2004. Science in China, Ser. D, 47(12): 1147–1154) for geostrophic small amplitude surface wave solutions and wave-induced tangential stress if the density of the upper layer is much smaller than that of the lower layer. The results show that the interface and the surface will oscillate synchronously, and the in.uence of the earth’s rotation both on the surface wave solutions and the interfacial wave solutions should be considered.     

两层粘性流体中圆柱体受迫振荡数值模拟

研究两层粘性流体中无限长水平圆柱体的受迫振荡问题。在湍流模式下,采用VOF方法追踪两层流体的内界面,基于动网格技术模拟圆柱体的运动边界,对均匀流中横向振荡圆柱体的绕流场进行了数值模拟。计算受迫振荡圆柱体的升力系数、阻力系数随时间的演化曲线和圆柱体的尾涡分布,以及圆柱体的受迫振荡激发两层流体内界面的扰动,并与均匀流体的情况进行了比较分析。研究表明,流体的两层分层效应对受迫振荡圆柱体的升阻力系数和尾涡分布特性都有显著影响,在水下输油气管道涡激振动特性的工程评估中,应考虑流体的密度分层效应。     

Hydroelastic Response of A Circular Plate in Waves on A Two-Layer Fluid of Finite Depth

The hydroelastic response of a circular, very large floating structure (VLFS), idealized as a floating circular elastic thin plate, is investigated for the case of time-harmonic incident waves of the surface and interfacial wave modes, of a given wave frequency, on a two-layer fluid of finite and constant depth. In linear potential-flow theory, with the aid of angular eigenfunction expansions, the diffraction potentials can be expressed by the Bessel functions. A system of simultaneous equations is derived by matching the velocity and the pressure between the open-water and the plate-covered regions, while incorporating the edge conditions of the plate. Then the complex nested series are simplified by utilizing the orthogonality of the vertical eigenfunctions in the open-water region. Numerical computations are presented to investigate the effects of different physical quantities, such as the thickness of the plate, Young’s modulus, the ratios of the densities and of the layer depths, on the dispersion relations of the flexural-gravity waves for the two-layer fluid. Rapid convergence of the method is observed, but is slower at higher wave frequency. At high frequency, it is found that there is some energy transferred from the interfacial mode to the surface mode.