| 题名 | 基于颗粒与流体耦合作用的被动式微流控芯片设计理论及实验研究 |
| 作者 | 周腾 |
| 学位类别 | 博士 |
| 答辩日期 | 2014-07 |
| 授予单位 | 中国科学院大学 |
| 导师 | 刘震宇 |
| 学位专业 | 机械制造及其自动化 |
| 中文摘要 | 微流控芯片系统近十年来在医学、生物和环境领域得到广泛应用。针对生物颗粒与细胞的检测，微流控芯片具有灵敏度高、试剂耗费低、方便携带、便于现场检测等优点。微流控芯片中对颗粒控制的方式分为主动式与被动式两种，其中被动式微流控芯片利用结构与流体交互作用对微米级尺度下流道内的流体运动与颗粒进行精确控制。本论文根据被动式微流控芯片控制方式的不同，研究了三种被动式微流控芯片。 随着雷诺数的增加流场中颗粒的惯性效应逐渐增强，因此惯性升力可以应用于高通量颗粒汇聚与分离。为了分析惯性微流体芯片对颗粒控制作用，本论文提出流场内颗粒拟稳态计算模型，颗粒旋转角速度与流场速度和压强耦合求解。本文首先分析而立二维流场中的颗粒受力状态，针对不同的雷诺数流场，通过参数扫描算法获得颗粒的受力平衡位置。在二维算例的基础上，进一步分析了球形颗粒在三维流场中的受力与平衡状态。此方法的优点在于颗粒平衡位置的求解仅需要网格在单维方向上进行变形，因此网格畸变可控，数值计算量小，平衡点位置较为精确。 液泳微流控芯片利用空间结构改变流场压力分布，进而改变颗粒表面受力。为了获得液泳微流控芯片中的颗粒轨迹，提高其对颗粒的汇聚效果，本文采用任意拉格朗日欧拉法（ALE）计算颗粒在液泳芯片的运动情况，系统分析了颗粒与管壁的交互作用，并通过实验验证了数值模拟的正确性。由于通过高速相机不能获得颗粒在流道深度方向上的运动轨迹，因此基于ALE的数值轨迹计算对于颗粒流芯片的设计具有重要的应用价值。通过详细对比颗粒轨迹与流线，表明仅在液泳芯片垂直面中心处流线可以替代垂直面中心处颗粒流固耦合计算。为了减少计算成本，本论文基于Faxen 定律提出一个无量纲优化目标来优化障碍尺寸参数，设计了颗粒快速汇聚微流控芯片。 收缩扩张结构能够对流体和颗粒产生惯性力与迪安（Dean）力作用，从而改变流体与颗粒的运动状态。本文首次采用拓扑优化方法对收缩扩张结构进行优化，并根据优化所得拓扑结构，提出由简单几何布尔运算构成的侧流结构，并依据此结构进行了单层混合器设计。依据混合单元，提出了三种不同的单元串行排列方式，探讨各自的混合效率随雷诺数的变化趋势。数值计算结果表明，优化后混合器相对原始的收缩扩张结构混合器有较大的雷诺数适用范围和较高的混合效率。 |
| 英文摘要 | The microfluidic system is wildly used in the field of biology, medical science, and environment science. In the past few years, it has gained significant advances. The passive microfluidic chips use the interaction between channel wall and hydrodynamics to control the movement of particle. In this thesis, three types of the passive microfluidic chips are discussed in succession. The inertia microfluidic emerged in recently years. In order to know how the inertia microfluidic device controls the particle, the pseudo-static model is proposed. The velocity field of fluid domains and the force acted on the particle is analyzed. Furthermore, the different inlet flow rates and particle positions are sweeped in order to obtain the equilibrium position of particle in fluid. The method can effectively avoid the mesh distortion and maintain the accuracy when the particle moves in the fluid. For passive sheathless particles focusing in microfluidics, the equilibrium positions of particles are typically controlled by micro channels with a V-shaped obstacle array (VOA). The design of the obstacles is mainly based on the distribution of flow streamlines without considering the existence of particles. We report an experimentally verified particle trajectory simulation using the arbitrary Lagrangian-Eulerian (ALE) fluid-particle interaction method. The particle trajectory which is strongly influenced by the interaction between the particle and channel wall is systematically analyzed. The numerical experiments show that the streamline is a good approximation of particle trajectory only when the particle locates on the center of the channel in depth. As the advantage of fluid-particle interaction method is achieved at a high computational cost and the streamline analysis is complex, a heuristic dimensionless design objective based on the Faxen's law is proposed to optimize the VOA devices. The optimized performance of particle focusing is verified via the experiments and ALE method. The contraction and expansion structure has the capability to twist flow streamline via the Dean and inertia effects. In this thesis, the topology optimization method is used to optimize the topology of the contraction and expansion structure. Based on the optimized topology geometry, the detailed lateral flow structure is simplified based on the boolean operation. One-layer mixer is designed via sequentially connected lateral structure and bent channels. The mixing efficiency is optimized via key geometric parameters of designed one-layer mixer. The numerical results illustrate that the proposed mixer has better mixing efficiency than the contraction-expansion mixer in relatively wide range of Re number cases. |
| 语种 | 中文 |
| 公开日期 | 2014-08-21 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.ciomp.ac.cn/handle/181722/41510]  |
| 专题 | 长春光学精密机械与物理研究所_中科院长春光机所知识产出 |
| 推荐引用方式 GB/T 7714 | 周腾. 基于颗粒与流体耦合作用的被动式微流控芯片设计理论及实验研究[D]. 中国科学院大学. 2014. |
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