990 resultados para Amplitude, number beams
Resumo:
This paper deals with turbulence behavior inbenthalboundarylayers by means of large eddy simulation (LES). The flow is modeled by moving an infinite plate in an otherwise quiescent water with an oscillatory and a steady velocity components. The oscillatory one aims to simulate wave effect on the flow. A number of large-scale turbulence databases have been established, based on which we have obtained turbulencestatisticsof the boundarylayers, such as Reynolds stress, turbulence intensity, skewness and flatness ofturbulence, and temporal and spatial scales of turbulent bursts, etc. Particular attention is paid to the dependences of those statistics on two nondimensional parameters, namely the Reynolds number and the current-wave velocity ratio defined as the steady current velocity over the oscillatory velocity amplitude. It is found that the Reynolds stress and turbulence intensity profile differently from phase to phase, and exhibit two types of distributions in an oscillatory cycle. One is monotonic occurring during the time when current and wave-induced components are in the same direction, and the other inflectional occurring during the time when current and wave-induced components are in opposite directions. Current component makes an asymmetrical time series of Reynolds stress, as well as turbulence intensity, although the mean velocity series is symmetrical as a sine/cosine function. The skewness and flatness variations suggest that the turbulence distribution is not a normal function but approaches to a normal one with the increasing of Reynolds number and the current-wave velocity ratio as well. As for turbulent bursting, the dimensionless period and the mean area of all bursts per unit bed area tend to increase with Reynolds number and current-wave velocity ratio, rather than being constant as in steady channel flows.
Resumo:
Tension leg platform (TLP) is an important kind of working station for deep water exploration and development in ocean, whose dynamic responses deserve a serious thought. It is shown that for severe sea state, the effects of nonlinearities induced by large displacements of TLP may be noteworthy, and then employment of small displacements model should be restrained. In such situation, large amplitude motion model may be an appropriate alternative. The numerical experiments are performed to study the differences of dynamic responses between the two models. It is shown that for most cases, differences between results of the two models are significant. The variances of the differences vs. the wave period are the most remarkable, and that of the differences vs. wave heading angle are also apparent.
Resumo:
本文集共收录了作者24篇期刊论文和研究报告。其中，1943～1955年期间发表的14篇论文内容涉及直管中的可压缩流动、有限振幅柱面和球面波的传播、可压缩流体二维无旋亚声速、超声速混合型流动和上临界马赫数、光滑跨声速绕流及其稳定性、斜激波从平板边界层的反射、中等雷诺数下绕平板的流动等。1956～1957年期间发表的5篇论文：绕平板和楔的高超声速流动、普朗特数和解离对高超声速流动的影响以及增补的5篇文章是作者在高超声速流动领域的研究成果以及他在回国后的学术报告和发表的文章，涉及现代空气动力学的发展方向、发射卫星和返地回收的科学和技术问题，体现了他在参与“两弹一星”技术领导工作中的学术思想。2 The flow of a compressible viscous fluid through a straight pipe.（可压缩黏性流体在直管中的流动1943年）
3 Two dimensional irrotational mixed subsonic and supersonic flow of a compressible fluid and the upper critical Mach number（可压缩流体二维无旋亚声速和超声速混合型流动及上临界马赫数1946年）
4 On the stability of transonic flows（论跨声速流的稳定性1947年）
5 The propagation of a spherical or a cylindrical wave of finite amplitude and the production of shock waves（有限振幅球面波或柱面波的传播及激波的产生1947年）
6 Two-dimensional irrotational transonic flows of a compressible fluid（可压缩流体二维无旋跨声速流动1948年）
7 On the hodograph method（关于速度图方法1949年）
8 Two-dimensional transonic flow past airfoils（绕翼型的二维跨声速流1951年）
9 On the stability of two-dimensional smooth transonic flows（论二元光滑跨声速流的稳定性1951年）
10 On the flow of an incompressible viscous fluid past a flat plate at moderate Reynolds numbers（中等雷诺数下不可压缩黏性流体绕平板的流动1953年）
11 Reflection of a weak shock wave from a boundary layer along a flat plate.I：Interaction of weak shock waves with laminar and turbulent boundary lavers analyzed by momentum-integral method（弱激波从沿平板的边界层的反射Ⅰ：用动量积分方法分析弱激波与层流和湍流边界层的相互作用1953年）
12 Reflection of weak shock wave from a boundary layer along a flat plate.Ⅱ：Interaction of oblique shock wave with a laminar boundary layer analyzed by differential-equation method（弱激波从沿平板的边界层的反射Ⅱ：用微分方程方法分析斜激波与层流边界层的相互作用1953年）
13 Plane subsonic and transonic potential flows（平面亚、跨音速势流1954年）
14 A similarity rule for the interaction between a conical field and a plane shock（锥型流和激波相互作用的相似律1955年）
15 Viscous flow along a flat plate moving at high supersonic speeds（沿高超声速运动平板的黏性流动【Ⅰ】1956年）
16 Viscous flow along a flat plate moving at high supersonic speeds（沿高超声速运动平板的黏性流动【Ⅱ】1956年）
17 The effects of Prandtl number on high-speed viscous flows over a flat plate（Prandtl数对绕平板高速黏性流的影响1956年）
18 Compressible viscous flow past a wedge moving at hypersonic speeds（楔的高超声速可压缩黏性绕流1956年）
19 Dissociation effects in hypersonic viscous flows（高超声速黏性流动中的离解效应1957年）
20 现代空气动力学的问题（1957年）
2l 在关于苏联发射成功第一颗人造卫星座谈会上的发言记录（1957年）
22 高超速钝体湍流传热问题（1963年）
23 宇宙飞船的回地问题（1965年）
24 激波的介绍
郭永怀生平
郭永怀传
Resumo:
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