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Modeling of the eddy viscosity by breaking waves 总被引：1，自引：1，他引：0
Breaking wave induced nearsurface turbulence has important consequences for many physical and biochemical processes including water column and nutrients mixing,heat and gases exchange across air-sea interface.The energy loss from wave breaking and the bubble plume penetration depth are estimated.As a consequence,the vertical distribution of the turbulent kinetic energy(TKE),the TKE dissipation rate and the eddy viscosity induced by wave breaking are also provided.It is indicated that model results are found to be consistent with the observational evidence that most TKE generated by wave breaking is lost within a depth of a few meters near the sea surface.High turbulence level with intensities of eddy viscosity induced by breaking is nearly four orders larger than υwl(=κuwz),the value predicted for the wall layer scaling close to the surface,where uw is the friction velocity in water,κ with 0.4 is the von Kármán constant,and z is the water depth,and the strength of the eddy viscosity depends both on wind speed and sea state,and decays rapidly through the depth.This leads to the conclusion that the breaking wave induced vertical mixing is mainly limited to the near surface layer,well above the classical values expected from the similarity theory.Deeper down,however,the effects of wave breaking on the vertical mixing become less important. 相似文献
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At present, most researches on the vortex-induced vibration of submarine free spanning pipelines ignore the effect of internal flowing fluid; furthermore, there are no research reports considering the coupling effect of internal and external fluid with the free span. In this paper, combining Iwan‘s wake oscillator model with the differential equation derived for the dynamic response of submarine free spanning pipelines with inclusion of internal flow, the pipe-fluid coupling equations are developed to investigate the effect of internal flow on the vortex-induced vibration of the free spans. The finite dement approximation is implemented to derive the matrix equations of equilibrium. The Newmark method combined with simple iteration is used to solve the system of equations. The results indicate that the internal fluid flow may cause the shift of resonance band to the lower frequency and a slight decrease in the peak value; the effect will be mare pronounced with the increase of the span length and can be weakened in the presence of the axial tension. 相似文献
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Experimental and Numerical Study of Wave-Induced Long-Shore Currents on A Mild Slope Beach 总被引：4，自引：0，他引：4
1.Introduction Long shorecurrenthasbecomethesubjectofextensiveworldwideresearchformanyyears.The purposeofthestudyistounderstandandpredicttheprocessesofsedimenttransport,shorelineevolu tionandpollutanttransportinthenear shorezoneundertheactionofwaves.Goda(2001)regarded thesuspendedsedimentastheprincipalloadinsedimenttransportandtheeffectoflong shorecurrents wasemphasized.Theeffectofwavesonpollutanttransportwasstudiedbynumericalmodelandfield experiment(TaoandHan,2002;Rodriguezetal.,1995),andth… 相似文献
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国外一些地质学家提出风暴流沉积、风暴岩.强调系暴风(台风)的突变性与灾变性力量形成的沉积物.据笔者对旋涡流作用成因的观察与研究得知,旋风(台风、龙卷风、气旋)是形成旋涡流的动力源之一.但旋风本身不能直接在海水中摄取砂粒形成沉积物,必须通过海水旋涡流作用,才能形成沉积,这又有违风暴流沉积说原意,而变成旋涡流沉积作用了.况且,旋风流动速度可与声速相当,延续时间短,形迹不定,不易搬运与形成沉积物. 相似文献
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基于GPU的大规模爆炸效果模拟 总被引：3，自引：0，他引：3
提出一种基于图形处理单元(GPU)的方法来模拟深空探测器撞击天体产生的大规模爆炸效果.利用基于GPU的多粒子系统方法模拟爆炸产生的3种喷射物,基于欧拉网格与漩涡粒子相结合的方法及GPU的通用计算能力解算流体动力学方程模拟了浓烟的翻腾与扩散.实验结果表明,用该方法能够产生具有较高逼真度的大规模爆炸效果. 相似文献
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Analysis using historical data on the phosphate sources in Changjiang （Yangtze River） estuary show that phosphate was supplied equally from the east, south, west and north of the estuary. These sources include the Changjiang River, the Taiwan Warm Current （TWC）, a cyclone-type eddy, and the 32°N Upwelling, supplying different phosphates in different times, ways and intensities. The magnitude of their supplying phosphate concentration was related with the size in the order of the Changjiang River 〈 the TWC 〈 the 32°N Upwelling 〈 the cyclone-type eddy, and the duration of the supplying was： the Changjiang River 〉 the TWC 〉 the cyclone-type eddy 〉 the 32°N Upwelling. The four sources supplied a great deal of phosphate so that the phosphate concentration in the estuary was kept above 0.2 pmol/L in previous years, satisfying the phytoplankton growth. The horizontal and vertical distribution of the phosphate concentration showed that near shallow marine areas at 122°E/31°N, the TWC in low nutrient concentration became an upwelling through sea bottom and brought up nutrients from sea bottom to marine surface. In addition, horizontal distribution of phosphate concentration was consistent with that of algae： Rhizosolenia robusta, Rhizosolenia calcaravis and Skeletonema, which showed that no matter during high water or low water of Changjiang River, these species brought by the TWC became predominant species. Therefore, the authors believe that the TWC flowed from south to north along the coast and played a role in deflecting the Changjiang River flow from the southern side. 相似文献
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一、什么是黑洞
黑洞,单单从这个名字看,就让人感觉神秘。事实上也的确如此,即使在天文学家的眼中,黑洞也是宇宙中最不寻常的天体。要介绍黑洞,先要从“逃逸速度”说起。 相似文献
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