拉格朗日-欧拉方法模拟高分子复杂流体平面收缩流动

为验证拉格朗日 欧拉方法的准确性 ,对高分子溶液的 4∶1平面收缩流动问题进行了数值模拟 ,采用单松弛时间的PhanThien Tanner本构方程 ,得到PIB/C1 4溶液在De =3 0的收缩流动的计算结果 ,同Quinzani等所做的收缩流动实验中的稳态流场物理量的测量结果进行了比较 ,在定量上取得较好的一致性 .证明拉格朗日 欧拉方法能够在定性上乃至在定量上准确地预报高分子复杂流体的流动行为 ,在描述真实的物理过程时是合理、准确的 .     

拉桥朗日—欧拉方法模拟高分子复杂流体平面收缩流动

为验证拉格朗日－欧拉方法的准确性,对高分子溶液的４：１平面刷缩流动问题进行了数值模拟,采用单松驰时间的Ｐｈａｎ Ｔｈｉｅｎ－Ｔａｎｎｅｒ本构方程,得到ＰＩＢ／Ｃ１４溶液在Ｄｅ＝３．０的收缩流动的计算结果,同Ｑｕｉｎｚａｎｉ等所做的收缩流动实验中的稳态流场物理量结果进行了比较,在定量上取得较好的一致性。证明拉格朗日－欧拉方法能够在定性上乃至在定量上准确地预报高分子复杂流体的流动行为,在描述真实的物理     

拉格朗日欧拉计算机模拟方法——对牛顿流体的解

用拉格朗日 欧拉方法模拟计算了各种流场中牛顿流体的流动问题 ,并以此来验证该算法的正确性 .其中 ,对具有准确解的二维Poiseuille流动、Couette流动以及同心圆筒间的流动 ,将模拟得到的数值解与数学解析解直接加以比较 ;对没有准确解的绕圆柱的平面流动、平面收缩和扩张流动 ,将模拟结果同一些已经发表的模拟或实验结果相比较 .从文中可见 ,该方法得到的各种结果都是合理、准确的 .     

聚合物复杂流体流动的动力学模拟

介绍聚合物复杂流体流动问题的模拟方法。通过比较,指出了经曲有限元方法的局限性和拉格朗日－欧拉方法在模拟复杂流动问题上的优越性。拉格朗日－欧拉方法的模拟结果同聚合物流体复杂流动的实验结果相一致,表明该方法在对复杂流体的动力学行为的模拟 合理的和可行的。     

高效液相色谱分离相似物质时二元流动相配比的选择

利用反相高效液相色谱中容量因子Ink′与二元流动相中强溶剂的体积分数Cb基本上成线性关系,再引入半峰宽数据(d),提出了用图解法来指导二元流动相配比选择的方法,从而使相邻两峰中小峰所对应的组分也能进行准确定量。方法具有简单、快速的优点。在实际应用中获得了满意的结果。     

反相高效液相法测定四环素类抗生素

 利用高效液相法 ,在C18柱上以甲醇 乙腈 0 0 1mol/L草酸溶液 (pH 2 0 ) (体积比为 11∶2 2∶6 7)为流动相 ,采用 2 6 7nm紫外光进行检测 ,在 2 2min内将 7种四环素类抗生素全部洗脱并达到基线分离。探讨了流动相的pH值、草酸的浓度、流动相中有机相的比例以及检测波长等因素对分离度和灵敏度的影响。采用标准加入法定量 ,对两种实际样品进行了分析。结果表明 :该方法操作简单、灵敏度高、定量准确。     

硅通孔内铜电沉积填充机理研究进展

上海交通大学多元兼容集成制造技术团队针对TSV互连的深孔填充电镀难题, 借助有限元软件和任意拉格朗日-欧拉算法, 完成了方程组的数值解算, 实现了TSV填充模式的数值仿真。利用有限元和任意拉格朗日-欧拉算法分析了盲孔的填充机制, 通孔的蝴蝶形式的电镀填充过程, 以及不同深宽比孔的同时填充模式,并利用仿真数据进行了样品的研制及参数优化。分析了电镀的电流密度和热处理温度对电镀填充TSV-Cu的力学属性的影响。通过原位压缩试验研究了电流密度对TSV-Cu的力学性能和显微组织的影响。利用单轴薄膜拉伸试验分析了热处理工艺对TSV-Cu材料属性的影响。结果表明, 随着热处理温度的升高, TSV-Cu的断裂强度和屈服强度明显下降, 杨氏模量呈波纹状变化但变化趋势缓慢。基于上述研究结果, 研究了热失配应力所导致的互连结构热变形机制, 通过自主搭建的原位测试系统,实时观测TSV-Cu随温度变化而产生的变形大小,以研究影响TSV-Cu互连热应力应变的规律。 结果表明, TSV-Cu 的热变形过程分为弹性变形阶段、类塑性强化阶段以及塑性变形阶段。     

氯磺隆的高效液相色谱分析方法研究

本文研究了用高效液相色谱法测定新型除草剂氯磺隆含量的方法,在反相ODS柱上,用甲醇—水作流动相进行洗脱,紫外225nm检测,以萘作内标定量,方法快速、灵敏、准确,氯磺隆的最小检出量为0.8ng,变异系数为1.4%,回收率为100.7%,一次分析仅需3分钟。     

非对称场流分离技术用于纳米颗粒的表征

采用非对称场流分离技术(Asymmetrical flow field-flow fractionation,AF4)对标准聚苯乙烯颗粒粒径进行表征。利用非对称场流分离仪以0.1%SDS(十二烷基磺酸钠)和0.02%NaN3的水溶液为流动相,测定标准的聚苯乙烯纳米颗粒在流体流场作用下通过分离腔室的保留时间,以确定纳米颗粒的平均粒径。优化了聚焦时间、横向流速、进样量、主体流速等实验条件,建立了利用AF4准确表征纳米颗粒的方法,并与扫描电镜(Scanning electron microscope,SEM)的表征结果进行比较。结果表明,AF4的表征结果比SEM更接近于聚苯乙烯颗粒的标准粒径,具有更高的稳定性和准确度。本方法可作为纳米粒径表征的一种准确方法。     

反相高效液相色谱法测定五肽胃泌素及其酶促降解产物

在反相ODS柱上,用NH_4Ac-HAc缓冲溶液和甲醇作流动相进行梯度洗脱,清晰地分离了五肽胃泌素及其酶促降解产物。HPLC法分离简便,定量准确,可有效地用于研究活性多肽的酶促降解机制。通过HPLC法探讨五肽胃泌素的降解过程尚属首次。     

TRANSIENT EFFECT OF A BOGER FLUID FLOWING AROUND A CONFINED CYLINDER

This paper is concerned with the numerical simulation of the transient effect of an inertialess Boger flow past aconfined circular cylinder and the comparison of predictions with particle image velocimetry (PIV) measurements given byShiang et al., Dynamic simulation based on the Oldroyd-B constitutive model was carried out using a Lagrangian-Eulerianalgorithm. The evolution of velocity field was obtained for the flow at two Deborah (De) numbers, i.e. De = 1.2 and 3.0. Atlow De, the flow reached steady state rapidly, and showed a symmetric flow regime. However, at high De, the time requiredto reach steady flow behind the cylinder increased significantly, and the distribution of the velocity field appears to beasymmetric with respect to the stagnation line. Fairly good agreement between the numerical results and the experimentalobservations is reported. It can be concluded that both the experimental measurements and the present simulations indicatethat the elasticity of the polymeric flow strongly affect the flow regime of viscoelastic flow around a confined cylinder.     

Evaluation of Calculating the Isotonic Swelling Ratio of Emulsion Liquid Membrane by Theoretical Viscosity Models

In this study, two viscous models, the Choi‐Schwalter and Phan‐Thien‐Pham models, are used to calculate the isotonic swelling ratio of emulsion liquid membrane. The purpose is to evaluate the usefulness of calculating isotonic swelling ratios of emulsion liquid membranes by viscous models through comparing theoretical isotonic swelling ratios with experimental swelling ratios of three kinds of emulsion liquid membranes. Comparison between theoretical swelling ratios and experimental swelling ratios indicates that experimental swelling ratios are close to those calculated by the Choi‐Schwalter model, but lower than those calculated by the Phan‐Thien‐Pham viscous model. But modified Phan‐Thien‐Pham viscous models predicts reasonable values. Therefore, the method of calculating the isotonic swelling ratio of emulsion liquid membrane by theoretical viscosity models is promising.     

Modeling microflow and stirring around a microrotor in creeping flow using a quasi-steady-state analysis

The microflow and stirring around paramagnetic particle microchains, referred to as microrotors, are modeled as a circular cylinder rotating about its radial axis at very low Reynolds number. Time scales for momentum transfer under these conditions are determined to be much smaller than those for boundary movement, hence a quasi-steady approximation can be used. The flow is derived at every instant from the case of a steady motion of a horizontally translating cylinder, with the rotation approximated to a series of differential incremental translations. A numerical simulation is used to determine the pathlines and material lines of virtual point fluid elements, which were analyzed to understand the behavior of the flow around the microrotor. The results indicate the flow to be unsteady, with chaotic advection observed in the system. The fluid motion is primarily two-dimensional, parallel to the rotational plane, with mixing limited to the immediate area around the rotating cylinder. Fluid layers, up to many cylinder diameters, in the axial direction experience the disturbance. Elliptic and star shaped pathlines, including periodic orbits, are observed depending on the fluid element's initial location. The trajectories and phase angles compare well with the experimental results, as well as with data from particle dynamics simulations. Material lines and streaklines display stretching and folding, which are indicative of the chaotic behavior and stirring characteristics of the system. The material lines have similar lengths for the same amount of rotation at different speeds, and the effect of rotational speeds appears to be primarily to change the time of mixing. The results are expected to help in the design of a particle microrotor based sensing technique.     

PPO/SEBS-g-MAH共混体系的形态结构与冲击性能

从亚微相态和冲击性能出发 ,对比了采用熔融挤出法制备的PPO/SEBS和PPO/SEBS g MAH两种共混物 .结果表明 ,在本文所研究的弹性体用量范围内 ,PPO/SEBS为“海 岛”型结构 ,而PPO/SEBS g MAH呈现网状结构 ;PPO/SEBS体系无脆韧转变现象 ,PPO/SEBS g MAH体系则在弹性体用量为 10 %～ 15 %时出现明显的脆韧转变 ,缺口冲击强度达到 95 0J/m ,这种超韧现象源于其网状结构的形成 .文中进一步用DSC和毛细管流变仪对共混体系的热性能和流变性能进行了测试 ,探讨了PPO/SEBS g MAH共混物网状结构的形成原因     

Bulles dans un écoulement de Couette-Taylor

This paper presents some experimental and numerical results about the presence of air bubbles as tracers in a highly turbulent Couette-Taylor flow with a superimposed axial flow and a top free surface. It appears that the air bubbles stand near the inner rotating cylinder, at every alternate boundary, corresponding to the outflow streamlines. © Académie des sciences/Elsevier, Paris     

Modeling of penetrant diffusion in glassy polymers with an integral sorption deborah number

A mathematical model was developed to explain the anomalous penetrant diffusion behavior in glassy polymers. The model equations were derived by using the linear irreversible thermodynamics theory and the kinematic relations in continuum mechanics, showing the coupling between the polymer mechanical behavior and penetrant transport. The Maxwell model was used as the stress–strain constitutive equation, from which the polymer relaxation time was defined. An integral sorption Deborah number was proposed as the ratio of the characteristic relaxation time in the glassy region to the characteristic diffusion time in the swollen region. With this definition, an integral sorption process was characterized by a single Deborah number and the controlling mechanism was identified in terms of the value of the Deborah number. The model equations were two coupled nonlinear differential equations. A finite difference method was developed for solving the model equations. Numerical simulation of integral sorption of penetrants in glassy polymers was performed. The simulation results show that (1) the present model can predict Case II transport behavior as well as the transition from Case II to Fickian diffusion and (2) the integral sorption Deborah number is a major parameter affecting the transition. © 1993 John Wiley & Sons, Inc.     

Residence time distribution from a continuous Couette flow device

This paper describes an experimental study of residence time distribution (RTD) by pulse response analysis in a continuous Couette flow device with rotating inner cylinder and stationary outer cylinder. The experiments were performed under conditions of (a) negligible and (b) significant influence of molecular diffusion and (c) Taylor vortex flow. Diethylene glycol and water were used as the test fluids with congo red dye and potassium permanganate solution as tracers respectively. A unique RTD described by an analytical expression was observed for experiments with low axial Reynolds number under the condition of negligible influence of molecular diffusion. For most experiments performed under conditions of significant influence of molecular diffusion and Taylor vortex flow regime over the ranges 0 < Ta < 118 and 0.4 < Re < 5.5, the RTD can be described by a dispersion model. The system behaves as a near-plug flow vessel at Ta ≈ 60. The critical Taylor number for this geometry as defined by the minimum dispersion number for a given flowrate is slightly higher than that without axial flow.     

一种新型单体引发转移终止剂合成精细结构功能化的聚苯乙烯

自从1982年Ｏｔｓｕ[1]等提出引发转移终止剂(Ｉｎｉｆｅｒｔｅｒ)以来,这类化合物得到了广泛的研究和发展.使用引发转移终止剂的聚合反应是实现“活性”聚合的一个重要方法.引发转移终止剂又分为热引发转移终止剂和光引发转移终止剂两种.热引发转移终止剂除了三苯甲基偶氮苯外[2],均是六取代乙烷类化合物[3～7];而光引发转移终止剂则一般是一些含二硫代氨基甲酰氧基基团的化合物,如Ｎ,Ｎ二乙基二硫代氨基甲酸苄酯(ＢＤＣ)、双(Ｎ,Ｎ二乙基二硫代氨基甲酸)对苯二甲酯(ＸＤＣ)、Ｎ乙基二硫代氨基甲酸苄酯(ＢＥＤＣ)、双(Ｎ乙基二硫代氨基甲酸…