多块网格技术及其在操纵面绕流计算中的应用

采用中心有限体积法求解Navier Stokes方程组,利用点对点搭接及面搭接多块网格技术成功地进行了多段翼型和存在外形间断(剪刀差)的带操纵面三维机翼的网格生成及粘性绕流流场数值计算,使用重叠面积加权插值及Ramshaw算法实现了面搭接的多块网格之间的信息传递并保证了通量守恒,并将流场计算结果与实验数据进行了对比.     

RICHTMYER-MESHKOV不稳定性的数值模拟

采用了自适应的非结构网格和基于有限体积法的二阶Godunov格式,数值模拟了在激波作用下两种不同密度流体的交界面的演化过程.着重讨论了Richtmyer Meshkov不稳定性以及斜压效应在交界面演化过程中的作用,并给出了交界面的扰动增长率.     

弗兰克—赫兹实验中的峰间距问题

运用吸收峰形成与变化判断准则解释了管温和阴－栅极距离对峰间距的影响。     

Rate of creation of the contacts between grains in a loose array of particles submitted to an uniaxial pressure

Macroscopic resistivity measurements have been performed on TiC/Al₂O₃ random mixtures submitted to uniaxial compression (0-95 kN). Such a random mixture exhibits an insulator-conductor transition which appears at increasing force while decreasing the conductive composition of the TiC/Al₂O₃ mixture. It is demonstrated that the conductivity behavior may be understood in the framework of a site percolation model. Finally, the rate of creation of the contacts between conductive grains is extracted from the macroscopic resistivity measurements. Received 6 December 2000 and Received in final form 30 March 2001     

Drug Release Study of Systems Containing the Tragacanth and Collagen Composite: Release Characterization and Viscoelastic Measurements

The kinetics of water penetration and pentoxifilline release from both Tragacanth gum and Tragacanth/Collagen matrices has been examined in pure deionised water. The rheological oscillatory measurements of their gel layer obtained by swelling of the imprinted pentoxifilline-filled polymer matrix with water have been performed. To qualify a polymer for application in drug formulation, appropriate gel stiffness is required. The aqueous solution of Tragacanth does not seem to acquire the actual strength that a hydrogel must retain for this purpose. Thus, along with Tragacanth, gelatin, CaCl₂ and 1, 8 octandiamine curing agent were individually blended in a mixture with Tragacanth gum to improve the gel behavior and drug delivery of the system. The strength of the gel at the body temperature (37 °C) was studied using a cone and plate rheometer. It was found that gelatin could enhance the gel strength of Tragacanth by forming a porous composite. The drug release to an aqueous solution at room temperature was analyzed to be slower for a composite of 1:2 Tragacanth/Collagen.     

可变形孔隙介质中热、水耦合力学问题的代数多格子分析方法

研究了孔隙介质中包括热和质量传递的全耦合多相流问题的代数多格子分析方法。数学模型包括质量、线性矩、能量平衡方程和本构方程,以位移、毛细压力、汽压和温度为基本变量,模型中采用了考虑毛细压力关系的修正有效应力概念,并考虑相变、热传导、对流和潜热交换(汽化-冷凝),气相是由易混合的干空气和水蒸气组成,视为理想气体。考题显示出较高的计算效率。     

多点择优推进阵面法生成曲面三角形网格

在现有曲面非结构网格生成法的基础上,提出了一种新的曲面网格生成法——多点择优推进阵面法.它可在曲面上直接进行三角形网格划分,克服了映射法的网格变形问题,并且可以在网格生成结束后,对曲面网格直接进行Laplace格点松弛光顺.该方法使用简单,不受曲面块类型的限制,且网格质量高,可以为三维非结构网格生成提供高质量的初始阵面,并给出了若干个算例.     

多段翼型粘性绕流多块网格数值模拟

采用多块结构网格和分区求解技术对多段翼型绕流进行雷诺平均NS方程数值模拟,并将计算的压力分布与实验进行了比较.     

Perturbational finite volume method for the solution of 2-D navier-stokes equations on unstructured and structured colocated meshes

IntroductionThefinitevolume (FV)methodusestheintegralformoftheconservationequationasitsstartingpointandcanutilizeconvenientlydiversifiedgrids(structuredandunstructuredgrids)andissuitableforverycomplexgeometry ,whicharewhyitispopularwithengineeringandhasbeenwidelyusedinagreatvarietyofcommercialsoftwareofcomputationalfluiddynamics.Relativetothefiniteelement (FE)methodandthefinitedifferential (FD)method ,thedisadvantageofFVmethodisthatitisnothigheraccuracy .FVmethodisofsecondlevelapproximatio…     

同位非结构和结构网格摄动有限体积法（PFV）求解二维Navier-Stokes方程组

根据NS方程组的一阶迎风和二阶中心有限体积（UFV和CFV）格式,导出NS方程组迎风和中心摄动有限体积(UPFV和CPFV)格式．该格式通过把控制体界面质量通量摄动展开成网格间距的幂级数,并由守恒方程本身求得幂级数系数而获得．迎风和中心摄动有限体积格式使用了与一阶迎风和二阶中心格式相同的基点数和相同的表达形式,宜于计算机编程．顶盖驱动方腔流和驻点流标量输运的数值实验证明,迎风PFV格式比一阶UFV、二阶CFV格式有更高的精度,更高的分辨率．尤其是良好的鲁棒特性．对顶盖驱动方腔流,在Re数从102到104范围内,亚松弛系数可在0.3～0.8任取,收敛性能良好．