Triangular temporal-distribution law for disintegrating internal solitons over a step

Internal solitary waves have been found to disintegrate into a series of solitons over variable bathymetry, with important applications for offshore engineering. Considering realistic background stratification in the South China Sea, internal solitary waves propagating over a step are studied here. By assuming disintegrated solitons propagate independently, a theoretical model, namely a triangular temporal-distribution law based on the Korteweg&ndash;de Vries theory, is proposed to describe the fission process of internal solitary waves undergoing disintegration. A parameter is then introduced to quantify the accuracy of the theoretical model. The results indicate that the triangular law predicts the fission process better for a longer travelling distance and a larger amplitude of internal solitary waves.</p

Effects of physical parameter range on dimensionless variable sensitivity in water flooding reservoirs

The similarity criterion for water flooding reservoir flows is concerned with in the present paper. When finding out all the dimensionless variables governing this kind of flow, their physical meanings are subsequently elucidated. Then, a numerical approach of sensitivity analysis is adopted to quantify their corresponding dominance degree among the similarity parameters. In this way, we may finally identify major scaling law in different parameter range and demonstrate the respective effects of viscosity, permeability and injection rate.</span

第十八届美国理论与应用力学大会总结

1会议概况2018年6月5—9日,第18届美国理论与应用力学大会(18th U.S. National Congress of Theoretical and Applied Mechanics, USNCTAM2018)在美国芝加哥召开.本次大会由美国力学国家委员会和中国力学学会联合主办,旨在探讨和交流近四年世界范围内在理论和应用力学领域的基础研究、创新技术的最新进展,吸引了来自世界各地的近千名专家学

Statistics of Turbulence in Benthal Boundary Layers

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

推移质输沙量的计算及其应用

基于推移质输沙率与水流动力条件之间的关系，提出了一种计算年平均推移质输沙量时，代表性水流动力条件的选择方法，同时将断面分为若干子断面进行计算，可以解决推移质沿断面不均匀输移的计算困难，计算过程中还考虑了推移质级配的逐时变化。所提出的计算方法应用于黄河青铜峡水库，计算了年平均推移质量，结果与实测淤积量符合很好

MECHANICS OF POROUS MEDIA FLOW:STATUS AND PERSPECTIVES

简述了水利、环境、能源工程和生物学中的渗流力学问题,扼要概括了渗流力学理论研究的现状,并指出渗流力学在多孔介质描述、裂缝型介质渗流、多相多组分渗流、物理化学渗流、非线性渗流、非饱和渗流、微观渗流、渗流模拟等理论及相关方法和测试技术等方面的发展趋势

Estimation of extreme hydrodynamic environments of Puti Island wind farm in Bohai Sea

In order to manifest the extreme hydrodynamic environments for Puti Island wind farm in Bohai Sea, flow and wave climates in the area induced by cold waves are investigated. According to the historical meteorology statistics and taking the global climate change into account, three typical paths (NNE, ENE and NNW) with four high wind speeds for cold waves in Bohai Sea are presumed. After calibrated with field data, the Princeton Ocean Model (POM) and the third-generation wave model, SWAN, are employed to delineate possible extreme hydrodynamic conditions in the area of Puti Island wind farm. The dependence of the extreme current and water wave parameters to the wind speed and wind direction is investigated. The distribution of the extreme current and water wave parameters in the wind farm is discussed. © 2017 The Author(s)

中国科学院力学研究所流固耦合系统力学重点实验室;

在严峻复杂的海洋动力条件下,自由表面大变形、破碎、飞溅的流动特性,及其对海洋结构物的非线性载荷,是海洋工程发展十分关注且急需解决的关键科学问题。关于非线性波浪载荷,人们基于势流和弱非线性假定发展了二阶分析理论,但应用于自由表面大变形的强非线性问题仍有很大局限。而较常采用的VOF等数值模拟方法很难准确模拟自由表面大变形、破碎、飞溅等强非线性特征。新近发展起来的追踪流体质点运动的无网格粒子法SPH,能够自动满足自由表面的界面追踪,对大变形的强非线性水波模拟有着独特的优势。因此,本文采用该方法,通过数值造波,研究强非线性波对直立圆柱的波载。水槽前端采用摇板和推板造波,模拟真实的实验水槽。造波板信号根..