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Transmission and Reflection of Water-Wave on a Floating Ship in Vast Oceans

Computers, Materials & Continua 2021年第6期67卷 2971-2988页

作者： Amel A.Alaidrous Department of Mathematics Faculty of Applied ScienceUmm Al-Qura UniversityMakkahSaudi Arabia

In this paper,we study the water-wave flow under a floating body of an incident wave in a fluid.This model simulates the phenomenon of waves abording a floating ship in a vast ocean.The same model,also simulates the phenomenon of fluid-structure interaction of a large ice sheet in waves.According to this method.We divide the region of the problem into three subregions.Solutions,satisfying the equation in the fluid mass and a part of the boundary conditions in each subregion,are given.We obtain such solutions as infinite series including unknown coefficients.We consider a limited number only of the coefficients by truncating the infinite series and satisfy the remaining boundary conditions approximately.Numerical experiments show that the results are acceptable.Tables are given along with the graph of the system of the resulting streamlines and the dynamical pressure acting on the obstacle.The drawn system of streamlines shows the correctness of the solution and the pressure is maximum on the side facing the upstream extremity of the channel.The same procedure can be adequately applied for problems with more complicated geometry and other phenomenon can thus be simulated.

关键词： Potential flow linear theory fixed floating obstacle fourier transformation boundary collocation technique spectral method

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Longitudinal Flight Dynamic Analysis on Vertical Takeoff of a Tailless Flapping-Wing Micro Air Vehicle

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Journal of Bionic Engineering 2018年第2期15卷 283-297页

作者： Loan Thi Kim Au Vu Hoang Phan Hoon Cheol Park Department of Advanced Technology Fusion and Artificial Muscle Research Center Konkuk University Seou105029 Korea

This paper first analyzed the longitudinal dynamic behavior during vertical takeoff without control of a Flapping-Wing Micro Air Vehicle （FW-MAV）. The standard linear flight dynamics based on small disturbances from trim condition was not applicable for our analysis because the initial flight condition, which was at rest on the ground, could be such a large disturbance from the trim condition that the linearization is invalid. Therefore, we derived linearized Equations of Motion （EoM） which can treat an untrimmed flight condition as a reference for disturbances. The Computational Fluid Dynamic （CFD） software ANSYS Fluent was used to compute the aerodynamic forces and pitching moments. Three flight modes were found： a fast subsidence mode, a slow subsidence mode and a divergence oscil- latory mode. Due to divergence oscillatory mode, the deviation from the reference flight grew with time; the FW-MAV tumbled without control. The simulation showed for the first 0.5 second after leaving the ground （the time that is long enough for delay of feedback control）, the FW-MAV flew up to a height of 6 cm with small horizontal and pitching motion, which is close to a vertical flight.

关键词： bioinspired FW-MAV flight dynamics vertical takeoff CFD linear theory

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Statistical Distribution of Surface Slope in A 3-D Ocean Wave Field

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China Ocean Engineering 2000年第3期15卷 289-296页

作者：徐德伦刘学海张军 Professor Physical Oceanography Laboratory Ocean University of Qingdao Qingdao 266003 P. R. China Research Assistant First Institute of Oceanography State Oceanic Administration Qingdao 266003 P. R. China Graduate student Physicatl Oceanography Laboratory Ocean University of Qingdao Qingdao 266003 P. R. China

A joint probability density function (PDF) for surface slopes in two arbitrary directions is derived on the basis of Longuet Higgins's linear model for three-dimensionol (3-D) random wave field. and the correlation moments of surface slopes. as parameters in the PDF, are expressed in terms of directional spectrum of ocean waves. So long as the directional spectrum model is given, these parameters are determined. Since the directional spectrum models proposed so far are mostly parameterized by the wind speed and fetch, this allows for substituting these parameters with thc wind speed and fetch. As an example, the wind speed and fetch are taken to be 14 m ' s and 200 km, and the Hasselmann and Donclan directional spectra are, respectively, use to compute these parameters. Some novel results a reobtained. One of the increasing interesting results is that the variances of surface slope in downwind and cross-wind directions determined by the Donclan directional spectra are close to those measured by Cox and Munk (1954). Some discussions are made on these results.

关键词： probability density function surface slope three-dimensional waves linear theory

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我国船舶水弹性力学研究的部分进展

我国船舶水弹性力学研究的部分进展

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作者：吴有生张效慈司马灿崔维成林吉如中国船舶科学研究中心

船舶水弹性力学在近20多年中取得了长足的进步,发展与应用船舶水弹性力学理论的领域越来越宽,内容越来越丰富。本文主要概述作者所在的中国船舶科学研究中心在船舶二维线性与非线性水弹性力学理论、三维线性频域与时域水弹性力学理论、... 详细信息

船舶水弹性力学在近20多年中取得了长足的进步,发展与应用船舶水弹性力学理论的领域越来越宽,内容越来越丰富。本文主要概述作者所在的中国船舶科学研究中心在船舶二维线性与非线性水弹性力学理论、三维线性频域与时域水弹性力学理论、三维二阶非线性船舶水弹性力学理论、航行中船舶甲板瞬态耦合动响应与动屈曲分析方法、弹性材料船模试验技术、翼鳍颤振的二维黏性流水弹性力学分析方法与黏性流体中非定常运动的水弹性力学方程、液体晃荡的水弹性力学分析方法、基于水弹性力学原理的船舶波浪载荷直接计算法、船舶水下爆炸动响应流固耦合理论等方面的研究内容,也介绍了国内的其它工作,以反映我国在该领域的研究状况之一斑。

关键词： hydroelasticity ships linear theory non-linear responses experiment

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