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571.
爆破挤淤填石法作为地基处理的一种常用方法,广泛应用于沿海养殖围堤、围海造地、护岸以及防波堤等水工工程的淤泥质软土地基处理。在对岱山樱连门促淤围垦工程围堤地基爆破挤淤处理产生的悬浮泥沙输移扩散进行模拟的基础上,分析了爆破挤淤对周围海域的影响。研究结果表明,爆破挤淤所产生的悬浮泥沙的输移扩散受潮流的影响较大,其输移扩散的范围及方向很大程度上取决于爆破后工程区域附近潮流的水动力强度及方向。爆破挤淤后产生的悬浮泥沙浓度增量由于扩散和沉降作用迅速减小,在爆破3 h后基本降至10 mg/L以下。爆破挤淤施工中产生的悬沙对周围的水环境虽然有一定的影响但持续时间并不长,且影响范围有限。 相似文献
572.
573.
晃荡是一种非常复杂的非线性液体流动现象,载液船舶的晃荡问题颇受关注,因为在外界的激励下液舱内会产生剧烈的晃荡现象,巨大的晃荡冲击力会造成结构的破坏.文中建立了三维晃荡数学模型及数值计算模型,借助处理自由表面的VOF(volume of fluid)方法对液舱内液体晃荡的自由表面进行追踪,编制程序实现了液舱内三维液体非线性晃荡的数值模拟,并就三维刚性液舱内粘性液体的自由晃荡和强迫晃荡做了分析,讨论了液体不同粘性系数对晃荡的影响.模拟结果证明了三维晃荡理论的可行性. 相似文献
574.
The problem of oblique wave(internal wave) propagation over a small deformation in a channel flow consisting of two layers was considered.The upper fluid was assumed to be bounded above by a rigid lid,which is an approximation for the free surface,and the lower one was bounded below by an impermeable bottom surface having a small deformation;the channel was unbounded in the horizontal directions.Assuming irrotational motion,the perturbation technique was employed to calculate the first-order corrections of the velocity potential in the two fluids by using Green’s integral theorem suitably with the introduction of appropriate Green’s functions.Those functions help in calculating the reflection and transmission coefficients in terms of integrals involving the shape function representing the bottom deformation.Three-dimensional linear water wave theory was utilized for formulating the relevant boundary value problem.Two special examples of bottom deformation were considered to validate the results.Consideration of a patch of sinusoidal ripples(having the same wave number) shows that the reflection coefficient is an oscillatory function of the ratio of twice the x-component of the wave number to the ripple wave number.When this ratio approaches one,the theory predicts a resonant interaction between the bed and the interface,and the reflection coefficient becomes a multiple of the number of ripples.High reflection of incident wave energy occurs if this number is large.Similar results were observed for a patch of sinusoidal ripples having different wave numbers.It was also observed that for small angles of incidence,the reflected energy is greater compared to other angles of incidence up to.These theoretical observations are supported by graphical results. 相似文献
575.
采用遗传算法进行球鼻艏优化的流体动力计算(英文) 总被引:1,自引:0,他引:1
Computational fluid dynamics(CFD) plays a major role in predicting the flow behavior of a ship.With the development of fast computers and robust CFD software,CFD has become an important tool for designers and engineers in the ship industry.In this paper,the hull form of a ship was optimized for total resistance using CFD as a calculation tool and a genetic algorithm as an optimization tool.CFD based optimization consists of major steps involving automatic generation of geometry based on design parameters,automatic generation of mesh,automatic analysis of fluid flow to calculate the required objective/cost function,and finally an optimization tool to evaluate the cost for optimization.In this paper,integration of a genetic algorithm program,written in MATLAB,was carried out with the geometry and meshing software GAMBIT and CFD analysis software FLUENT.Different geometries of additive bulbous bow were incorporated in the original hull based on design parameters.These design variables were optimized to achieve a minimum cost function of "total resistance".Integration of a genetic algorithm with CFD tools proves to be effective for hull form optimization. 相似文献
576.
In this research,liquid sloshing behavior in a 2-D rectangular tank was simulated using ANSYS-FLUENT software subject to single or multiple-coupled external excitations(such as sway coupled with roll,and sway and roll coupled with heave).The volume of fluid(VOF) method was used to track the free surface of sloshing.External excitation was imposed through the motion of the tank by using the dynamic mesh technique.The study shows that if the tank is subjected to multiple coupled excitations and resonant excitation frequencies,liquid sloshing will become violent and sloshing loads,including impact on the top wall,will be intensified. 相似文献
577.
Guoxiong Wu 《船舶与海洋工程学报》2012,11(2):143-149
A high order boundary element method was developed for the complex velocity potential problem. The method ensures not only the continuity of the potential at the nodes of each element but also the velocity. It can be applied to a variety of velocity potential problems. The present paper, however, focused on its application to the problem of water entry of a wedge with varying speed. The continuity of the velocity achieved herein is particularly important for this kind of nonlinear free surface flow problem, because when the time stepping method is used, the free surface is updated through the velocity obtained at each node and the accuracy of the velocity is therefore crucial. Calculation was made for a case when the distance S that the wedge has travelled and time t follow the relationship s=Dtα, where D and α are constants, which is found to lead to a self similar flow field when the effect due to gravity is ignored. 相似文献
578.
以某(88+152+88)m连续梁桥为工程背景,建立了采用液体黏滞阻尼器(FVD)的减震模型,采用非线性动力时程分析方法研究粘滞阻尼器对该桥抗震性能的影响。通过粘滞阻尼器在不同位置的布设,得出了最优的布置方案;通过基于阻尼力的参数分析,得出了最优的阻尼器型号。研究结果表明:"-3地震力较大时,单独采用阻尼器并不能完全达到理想的效果,此时,设置减震专用支座(SSAB)与阻尼器配合使用可进一步改善桥墩受力;减震专用支座可按滞后系统进行模拟,分析时可基于2种极端状况来模拟其恢复力模型,取屈服强度为设定的减震专用支座水平力限值时计算结果可控制设计。 相似文献
579.
在考虑大变形、忽略阻尼的影响下,基于有限元软件ANSYS分析了加筋板在流固冲击载荷下的非线性瞬态响应.不仅将不同的冲击载荷形式,譬如阶跃载荷和三角形载荷,与流固冲击载荷对加筋板动力特性的影响进行了比较,还分别讨论了载荷峰值、冲击载荷持续时间、板厚、加强筋材料体积比和截面宽高比的影响,并对它们作了敏感度分析. 相似文献
580.
基于流体分析的工业结晶器搅拌桨结构优化 总被引:2,自引:0,他引:2
通过对结晶器搅拌桨的结构分析,以螺距比h/D,盘面比Ag/Ao和筒径比d/D′等为参数实现搅拌桨的参数化设计,以结晶器内各点流速均匀分布为原则,用通用流体力学分析软件Fluent对釜内流场进行了定量分析,确定最优参数为.h/D=1.2,AE/A0=0.7,d/D′=0.63. 相似文献