Nearest neighbor search algorithm based on multiple background grids for fluid simulation

The core of smoothed particle hydrodynamics (SPH) is the nearest neighbor search subroutine. In this paper, a nearest neighbor search algorithm which is based on multiple background grids and support variable smooth length is introduced. Through tested on lid driven cavity flow, it is clear that this method can provide high accuracy. Analysis and experiments have been made on its parallelism, and the results show that this method has better parallelism and with adding processors its accuracy become higher, thus it achieves that efficiency grows in pace with accuracy.     

产学研联盟中知识流的动力学模型构建与仿真

为进一步揭示产学研联盟中的知识流动规律,将流体力学引入到产学研联盟的知识流研究中,定义知识流的密度、压力等概念,结合联盟中知识分流和知识粘滞的情况,建立的联盟知识流的连续性方程和运动微分方程,构造出联盟知识流的动力学模型。对模型数值模拟结果表明,加强外部驱动力、降低知识粘性能够促进联盟知识的流动,异质知识的流入会对当前渠道的知识流产生粘滞阻力影响。     

流体力学教学技巧探讨

流体力学是热能与动力工程专业的专业基础课。本文针对流体力学课程的特点,对流体力学的教学方法进行了探讨,提出了提高教学效果应该注意的问题,供从事本课程教学工作的教师参考。     

工程流体力学实验教学的改革与创新

文章针对工程流体力学实验教学中存在的问题,从实验教学内容、实验教学方法和手段、实验考试制度等方面进行深入细致地分析,结合教学实际,进行了改革与创新的探索,并提出了一些有益的方法和建议。     

Numerical Simulation of Shaped Charge Jet Using Multi-Phase SPH Method

Since the jets and detonation gaseous products are separated by sharp interfaces,the traditional smoothed particle hydrodynamics (SPH) method is difficult to avoid the computational instability at interfaces.The multi-phase SPH (MSPH) method was applied to improving the stability,which smoothes the particle density and makes pressure continuous at interfaces.Numerical examples of jet forming process were used to test capability of the MSPH method.The results show that the method remains algorithm stability for large density gradient between the jets and gaseous products and has potential application to both the explosion and the jet problems.The effect of initiation ways of the shaped charge was discussed as well.     

国内外体育工程学的研究综述

体育工程学是一门崭新的学科,最近十几年得以飞速发展,其研究领域越来越广泛。我国也开展了一些相关的研究,但在研究的广度和深度上与国际还有一定差距。武汉地区的体育工程学主要系统地开展水上运动项目的研究工作,目前,已经基本形成了比较完整的研究体系和从教练员岗位培训到硕士、博士和博士后研究人员的人才培养体系。另外,武汉地区的体育工程学的发展十分注重学科的整合,注重理工科和体育院校联合开展学术研究和人才培养。     

Determination of a quantitative parameter to evaluate swimming technique based on the maximal tethered swimming test

The aim of this study was to propose a new force parameter, associated with swimmers’ technique and performance. Twelve swimmers performed five repetitions of 25 m sprint crawl and a tethered swimming test with maximal effort. The parameters calculated were: the mean swimming velocity for crawl sprint, the mean propulsive force of the tethered swimming test as well as an oscillation parameter calculated from force fluctuation. The oscillation parameter evaluates the force variation around the mean force during the tethered test as a measure of swimming technique. Two parameters showed significant correlations with swimming velocity: the mean force during the tethered swimming (r = 0.85) and the product of the mean force square root and the oscillation (r = 0.86). However, the intercept coefficient was significantly different from zero only for the mean force, suggesting that although the correlation coefficient of the parameters was similar, part of the mean velocity magnitude that was not associated with the mean force was associated with the product of the mean force square root and the oscillation. Thus, force fluctuation during tethered swimming can be used as a quantitative index of swimmers’ technique.     

Dynamical Behavior of Core ~3 He Nuclear Reaction-Diffusion Systems and Sun′s Gravitational Field

IthasbeenlongunderstoodthatthegravityplaysavitalroleinsuchinstabilityofhydrodynamicsastheBenardconvection. Itisworthnoticing, forareac tion diffusionsystem, thegravityfieldcouldbringaboutinhomogeneityinspace, leadingtothebreakofspacesymmetryandthenintroducingthepreferenceforstates[1]. Intheinteriorofastar, thecorenuclearreactionsareaffectedalwaysbythegravitationalfield,thepressure, thediffusionofparticlesandthemotionoffluid, amongwhichthegravitationalfieldwasbe lievedtobeareasonfordrivingt…     

双极量子流体力学模型的弱解的恒正性

文章研究次音速条件下双极量子流体力学模型正解的存在性.先将原方程组变形为常见的形式,得到原问题的等价问题利用先验估计和Leray-Schauder不动点定理证明了无论是等熵还是等温条件下,对于所有的电流密度,此模型存在正解.     

Dynamical Behavior of Core 3 He Nuclear Reaction-Diffusion Systems and Sun''s Gravitational Field

The coupling of the sun's gravitational field with processes of diffusion and convection exerts a significant influence on the dynamical behavior of the core 3He nuclear reaction-diffusion system. Stability analyses of the system are made in this paper by using the theory of nonequilibrium dynamics. It is showed that, in the nuclear reaction regions extending from the center to about 0.38 times of the radius of the sun, the gravitational field enables the core 3He nuclear reaction-diffusion system to become unstable and, after the instability, new states to appear in the system have characteristic of time oscillation. This may change the production rates of both 7Be and 8B neutrinos.