共查询到14条相似文献,搜索用时 62 毫秒
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以三维圆柱为研究对象,使用Lighthill声类比法研究其绕流发声问题。第一步进行流场计算,分别用大涡模拟(LES)、脱体涡模拟(DES)和瞬态雷诺平均法(URANS)模拟声源区流场,通过对比流场压力和涡量等参数,据此选取合适的流场仿真方法;第二步用基于Lighthill方程FW-H积分法和边界元法预报远场直发声,通过和Revell试验结果比较,分析各种计算方法差别。研究表明:进行流场仿真时LES计算结果最好,IDDES法在保证计算精度条件下能有效减少流场网格数量,URANS法误差很大;进行辐射噪声预报时,FW-H积分法和边界元法基本相同。 相似文献
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典型夏季海洋环境噪声垂直指向性水平方向经常出现一显著凹槽。采用三维声速场海洋环境噪声理论模型,分析了各阶简正波对垂直指向性的贡献,指出不同阶简正波的贡献不同,高阶简正波是形成水平方向凹槽的主因,低阶简正波起填补环凹槽的主要作用,无内波时海面噪声源激发低号简正波的能量较低,填补能力较差,水平凹槽显著;内波活动期,内波改变了声信号的传播路径,引起不同阶简正波耦合,低号简正波能量增强,其填补噪声水平凹槽的作用明显加强,高阶简正波能量减少,凹槽变浅。还探讨了凹槽填补程度与内波强度之间的关系,以及有内波时环境噪声垂直指向性随时间的变化。 相似文献
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利用浅海环境噪声进行海底特性反演一直是学者们研究的热门课题之一,当考虑两层海底时,由于待反演参数较多,基于传统遗传算法的反演策略往往使反演过程陷入局部最小值,从而无法找到全局最优解。针对两层海底的情况,计算得到了浅海环境噪声场空间相干性的表达式,并对传统遗传算法进行了改进,通过引进自适应交叉和变异算子以及能够保持种群多样性的小生境技术来提高反演算法的性能。通过数值仿真,验证了改进后的算法较传统算法能更好地收敛到真实值;并针对一次海试数据进行了海底特性反演,获得了较好的结果。 相似文献
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利用环境噪声反演浅海海底声学特性一直是学者们研究的热门课题之一,目前绝大多数的噪声场建模方法依赖于多维海底模型,而多维参数的求解过程加大了反演的复杂度。减少反演参数个数可以有效降低反演的复杂性,提高反演的速度,以此为目的开展了基于单个参数海底模型的噪声场建模研究,并计算得到了基于海底单参数的噪声场空间相干系数表达式。通过与传统模型的对比,验证了该计算模型的有效性。结合实验数据,利用该模型对实验海域进行了海底单参数反演,并结合海底反射临界角确定了实验海域的沉积物类型为粉砂质砂,该结论与文献记载相吻合。 相似文献
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Enrique Ortega Eugenio Oñate Chinapat Buachart 《International journal for numerical methods in engineering》2011,88(2):180-204
An adaptive Finite Point Method (FPM) for solving shallow water problems is presented. The numerical methodology we propose, which is based on weighted‐least squares approximations on clouds of points, adopts an upwind‐biased discretization for dealing with the convective terms in the governing equations. The viscous and source terms are discretized in a pointwise manner and the semi‐discrete equations are integrated explicitly in time by means of a multi‐stage scheme. Moreover, with the aim of exploiting meshless capabilities, an adaptive h‐refinement technique is coupled to the described flow solver. The success of this approach in solving typical shallow water flows is illustrated by means of several numerical examples and special emphasis is placed on the adaptive technique performance. This has been assessed by carrying out a numerical simulation of the 26th December 2004 Indian Ocean tsunami with highly encouraging results. Overall, the adaptive FPM is presented as an accurate enough, cost‐effective tool for solving practical shallow water problems. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Shahrouz Aliabadi Muhammad Akbar Reena Patel 《International journal for numerical methods in engineering》2010,83(13):1719-1738
A hybrid numerical scheme based on finite element and finite volume methods is developed to solve shallow water equations. In the recent past, we introduced a series of hybrid methods to solve incompressible low and high Reynolds number flows for single and two‐fluid flow problems. The present work extends the application of hybrid method to shallow water equations. In our hybrid shallow water flow solver, we write the governing equations in non‐conservation form and solve the non‐linear wave equation using finite element method with linear interpolation functions in space. On the other hand, the momentum equation is solved with highly accurate cell‐center finite volume method. Our hybrid numerical scheme is truly a segregated method with primitive variables stored and solved at both node and element centers. To enhance the stability of the hybrid method around discontinuities, we introduce a new shock capturing which will act only around sharp interfaces without sacrificing the accuracy elsewhere. Matrix‐free GMRES iterative solvers are used to solve both the wave and momentum equations in finite element and finite volume schemes. Several test problems are presented to demonstrate the robustness and applicability of the numerical method. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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海洋环境噪声垂直指向性是声呐背景场的典型空间特性之一,既可体现噪声源的空间特性及其传播特性,还可用来反演海洋环境的特征参数。分析了南海某岛礁海域实测海洋环境噪声的垂直指向性,发现当接收阵远离航道时,低频海洋环境噪声垂直指向性的主瓣集中在-30°~30°范围内(0°对应水平方向),且水平方向不存在凹槽。基于舰船自动识别系统(Automatic Identification System, AIS)航船分布数据得到简化航道区域航船噪声源模型,利用3D射线声传播算法,结合实际岛礁海域地形数据,计算的低频海洋环境噪声垂直指向性与实测数据处理结果相符。研究结果表明,当接收阵距航道较远时,由航道航船引起的低频海洋环境噪声以接近水平方向入射垂直接收阵,研究结果可为声呐在远离航道海域的性能提高提供技术支持。 相似文献