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基于海浪波面的随机特性,研究船舶底部砰击压力的计算方法.分析纵向入水角对船底砰击压力量值的影响程度,建立二者之间的定量关系.在预报船舶砰击压力时引入随机海浪的波面条件,计及船舶运动和海浪波面倾角因素对砰击压力的影响.采用蒙特卡罗数值模拟法对砰击压力的统计规律进行研究,结果表明:计及纵向入水角的船底砰击压力计算方法.更加... 相似文献
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A sigma (σ)-coordinate ocean model by Blumberg and Mellor (POM) is applied to study the formation processes of mesoscale cyclones observed in the Eastern Gotland Basin following the dense water inflows. The initial conditions simulate a situation when the Arkona and Bornholm basins and partially the Slupsk Furrow are already filled with the inflow water of the North Sea origin, while the Eastern Gotland and Gdansk basins still contain the old water of pre-inflow stratification. Model runs with constant and time-dependent winds, changing the buoyancy forcing, grid geometry and bottom topography display the following. Entering the Eastern Gotland Basin from the Slupsk Furrow, the bottom intrusion of saline inflow water splits in two: one goes northeast towards the Gotland Deep, and second moves southeast towards the Gulf of Gdansk. An intensive mesoscale cyclonic eddy carrying the inflow water is generated just east of the Slupsk Furrow with the inflow pulse. A number of smaller cyclones with boluses of the inflow water are formed in the permanent halocline along the saline intrusion pathway to the Gotland Deep. Following Spall and Price [J. Phys. Oceanogr. 28 (1998) 1598], the cyclones are suggested to form by the adjustment of the high potential vorticity inflow water column to a low potential vorticity environment. 相似文献
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In this study, current meter and hydrological data obtained during the X Italian Expedition in the Ross Sea (CLIMA Project) are analyzed. Our data show a nice agreement with previous data referring to the water masses present in this area and their dynamics. Here, they are used to further analyze the mixing and deepening processes of Deep Ice Shelf Water (DISW) over the northern shelf break of the Ross Sea. In more detail, our work is focused on the elementary mechanisms that are the most efficient in removing dense water from the shelf: either classical mixing effects or density currents that interact with some topographic irregularity in order to drop to deeper levels, or also the variability of the Antarctic Circumpolar Current (ACC) which, in its meandering, can push the dense water off the shelf, thus interrupting its geostrophic flow. We also discuss in detail the (partial) evidence of dramatic interactions of the dense water with bottom particulate, of geological or biological origin, thus generating impulsive or quasi-steady density-turbidity currents. This complex interaction allows one to consider bottom particular and dense water as a unique self-interacting system. In synthesis, this is a first tentative analysis of the effect of bottom particulate on the dense water dynamics in the Ross Sea. 相似文献
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Odd M. Faltinsen 《Journal of Marine Science and Technology》2000,5(2):49-65
An overview of the many water-impact (slamming) problems in ship and ocean engineering is given. Theoretical and experimental
drop tests of horizontal and nearly horizontal elastic plates are reviewed. It is shown that maximum pressure cannot be used
to estimate maximum slamming-induced stresses when maximum pressure is large, because dynamic hydroelastic effects then become
important. Further, the significance of hydroelasticity increases with decreasing dead-rise angle, increasing impact velocity,
and increasing the value of the highest local natural period of the structure. It is emphasized that the slamming problem
must be hydrodynamically studied from a structural point of view. Comparisons between theory and full-scale measurements of
slamming-induced local strains in the wet-deck of a catamaran are presented. The importance of the rigid body vertical accelerations
and the influence of the side-hulls on the impact velocity are pointed out.
Received: October 4, 2000 相似文献
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文章基于ALE理论,建立了高速物体砰击水面的三维有限元模型,通过数值计算,分析研究了物体质量、水平初速度、竖直方向初速度、水深和水面宽度分别对高速物体砰击水面后弹起高度和水平方向位移的影响.研究结果对工程中诸如民航飞机水上迫降、水上飞机水上降落等的初始参数优化具有重要的参考价值. 相似文献
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