平均－分散輸送モデルの閉路解決法

電気通信大学201

Numerical simulation about trapping two particles in microfluidic dielectrophoretic chip

In this paper, we calculated the spatial locally averaged velocity strains along the streamwise direction with four scales in the velocity vector field of turbulent boundary layer by utilizing the three-dimensional three-component database of time series of velocity field measured by tomographic time-resolved particle image velocimetry. We introduced an improved quadrant splitting method based on the spatial local-averaged velocity strains and a new conditional sampling phase average method as a data-mining criterion to detect and extract the inherent coherent structures from such turbulence signal database. Furthermore, we used the improved quadrant splitting method to obtain and investigate the spatial topologies of fluctuating velocity and fluctuating vorticity with four scales whose center was a strong second-quadrant event (Q2) or a fourth-quadrant event (Q4). Results illustrate that there is a better similarity of the multi-scale coherent structures in wall-normal direction than the one in other two dimensions. © 2012 IEEE

平均－分散輸送モデルの閉路解決法

201

基于直接数值模拟的EMMS模型稳定性条件验证

气固流态化系统是典型的非平衡系统，呈现出复杂的时空多尺度结构，因而需要使用多尺度方法进行分析。能量最小多尺度(EMMS)模型揭示了介尺度结构及稳定性条件在认识气固流态化系统中的重要作用，在气固流态化系统中得到了广泛应用。本文致力于通过直接数值模拟(DNS)分析流态化不均匀结构，构造气固流态化系统的能耗统计方法，同时对EMMS模型中提出的稳定性条件，即流体悬浮输送单位质量颗粒的能耗Nst趋于最小进行验证。对比基于拟颗粒模型（PPM）的验证工作，本文通过引入加速度并考虑不同颗粒初始分布方式使结论更有说服力，并且基于DNS的研究可以更准确的统计能耗项。本论文各章内容安排如下：第1章 对气固流态化系统进行介绍，并综述了包括实验、经验公式及数值模拟方法在内的研究成果，同时说明三类常用的数值模拟方法：双流体模型(TFM)、颗粒轨道模型以及直接数值模拟的优缺点，阐明了选择直接数值模拟开展本工作的原因。第2章 详细介绍了本论文中采用的直接数值模拟方法，包括流场求解、颗粒运动处理以及流固耦合方式，并通过模拟流体流过静止单颗粒及交错分布的颗粒群验证了数值模拟方法的准确性。第3章 在EMMS模型中悬浮输送流速的统计中考虑加速度的影响，对不同颗粒初始分布方式、不同入口气速的气固流态化体系进行了模拟，得到了悬浮输送流速Ust随时间趋于最小的结论，验证了EMMS模型稳定性条件。第4章 对本论文内容进行总结并对未来的工作进行了展望，目前对EMMS模型稳定性条件的验证仍延续着间接求解的方法，将来随着EMMS模型中的能耗项与气固流态化的能量系统建立更完善的对应关系，通过直接数值方法对EMMS模型中能耗项进行统计将是非常有前景的研究方向。;The gas-solid fluidization system is a typical non-equilibrium system, which presents a complex multi-scale structure of space and time. The energy minimum multi-scale (EMMS) model reveals the important role of mesoscale structures and stability conditions in gas-solid fluidization systems, and it has been widely used in gas-solid fluidization systems.In this paper, direct numerical simulation (DNS) is used to analyze the fluidized heterogeneous structure and to construct the energy consumption statistics method of gas-solid fluidized system. The stability condition proposed by the EMMS model is that the energy consumption Nst for suspending and conveying unit mass particles tends to minimum is proved in this thesis.Compared with validation work using the Pseudo-Particle Modeling (PPM), the acceleration is introduction and differnet initial distributions of particles is considered in this thesis to make the conclusion more persuasive, and the statistics of energy consumption based on DNS is more accurate.The main contents of this thesis are as follows: In chapter 1, gas-solid fluidization system and its non-uniform structure is introduced, and reviews the research results of experiment, empirical formula and numerical simulation method. Illustrates the merit and demerit of three kinds of numerical simulations including two-fluid model, Eulerian-Lagrangian method and direct numerical simulation, in order to explain why we choose direct numerical simulation to study the gas-solid fluidization;In chapter 2, the DNS method used in this paper is introduced in detail, including flow field solution, particle motion treatment and fluid-solid coupling method. The rationality of the DNS method is verified by simulating the fluid through a single particle and fluid through staggered distribution of the particles.In chapter 3, the influence of acceleration is considered in the statistics of suspension and transport velocity in the EMMS model. The gas-solid fluidization systems with different initial particle distribution patterns and different inlet velocity are simulated using DNS. The conclusion that the suspension and transport velocity Ust tends to be minimized with time is obtained, and the stability condition of the EMMS model is verified.In chapter 4, the main results in this thesis is summarized and some future directions on DNS is discussed. The validation of stability conditions of the EMMS model in this thesis still uses the indirect statistical method. In the future, as the energy consumption terms in the EMMS model correspond better with the energy system of gas-solid fluidization, counting the energy consumption terms in the EMMS model directly with DNS would become a very promising research direction.&nbsp;</p

単層カーボンナノチューブのCVD合成制御と太陽電池応用

学位の種別: 課程博士審査委員会委員 : (主査)東京大学教授 丸山 茂夫, 東京大学教授 大久保 達也, 東京大学教授 染谷 隆夫, 東京大学准教授 加藤 雄一郎, 東京大学講師 米谷 玲皇, 東京大学講師 千足 昇平University of Tokyo(東京大学

微尺度流动特性

通过微推进器小型化的具体问题说明微型化不是简单的尺寸缩小。微尺度流动所基于的物理因素与宏观流动不同，体现在流动涉及的表面积与体积之比增强、梯度参数效应及界面力效应等，物理因素作用的改变或新的因素参与，使微尺度流动呈现新的特点，这为设计芯片和传感器中的流动提供了新的思路，正如文中介绍的增强层流混合方法。微尺度效应在流体力学理论方面也会有所体现，包括对基本方程、边界条件的修正，然而对流动现象的深入认识则是理论发展的关键。简单介绍了作者的研究组在微尺度液体流动实验方面的研究结果

硅中铂族金属掺杂剂的萃取分离及测定

本工作采用溶剂萃取分离法及石墨炉原子吸收测定法建立了分离Pd-Pt-Ir及Pd-Rh-Ir的方法, 分析测定了掺Pd-Pt, Pd-Pt-Ir及Pd-Rh-Ir的硅样品中铂族元素在硅中的纵向分布

浅析跨地区企业分支机构内部审计

内部审计是提高企业管理水平、加强风险防控能力的有效措施.尤其是对于集团企业而言,其分支多、区域跨度大,因而内部审计显得尤为重要.本文将以跨地区企业为研究对象,简述内部审计的内涵以及意义,对审计过程中存在的问题进行分析,并提出可行性建议,旨在为我国企业审计水平的提升提供一定参考借鉴.</p