基于格子Boltzmann方法的T型微混合器仿真模拟

发布时间：2018-05-28 04:44

本文选题：格子Boltzmann方法 + T型微混合器　；参考：《东北大学》2012年硕士论文

【摘要】：微机电系统(micro electro mechanical systems, MEMS)是指基于集成电路工艺设计制造并集电子元件与机械器件于一体的微小系统。微混合器作为MEMS的重要组成部件,目前已越来越受到重视,对微尺度流动和液体混合的研究也变得越发重要。物理体系的研究方法可以分为理论研究,实验研究和数值模拟三大类,随着计算机技术的快速发展,数值模拟技术得到了越来越多的重视以及更广泛的应用。格子Boltzmann方法(LBM)作为一种全新的介观模拟方法在近20年得到了快速的发展。LBM既可以分析不连续流场,又相对节约计算量的特点使其在模拟微流体流动和建模方面取得了重要进展。本文基于LBM来对微混合器中流体的混合问题进行模拟。首先介绍了LBM的基础理论,对Boltzmann方程进行了详细的推导,介绍了一些LBM的基本模型和边界处理方法。然后,通过对流体力学中三个典型实例的仿真模拟验证了LBM的可行性与准确性,期间引入了混合指标σ-来评价混合效果的好坏。最后将LBM应用到微混合器流体混合的模拟中,对简单T型微混合器和内肋型微混合器进行了数值模拟,得出了不同的影响因素对混合效果的影响曲线。其中,对于简单T型微混合器,有如下结论：入口速度越小,混合效果越好；混合通道宽度越小,混合效果越好,但混合指数的变化十分微小；碰撞系数越大,流体扩散越快,混合效果越好；粘度系数越大,混合效果越差。对于内肋型微混合器,有：流体的混合效果随着入口速度的减小呈现先变差后边好的趋势；碰撞系数对于高速条件下的混合几乎没有影响,对于低速条件下影响明显；内肋板的长度越大,流体的混合效果越好；周期长度越大,流体的混合效果越差,但混合指数的变化并不大。最后,本文对两种微混合器在不同入口速度条件下的混合性能进行了对比,内肋型微混合器要远远优于简单T型微混合器。
[Abstract]:Micro electro mechanical systems, MEMS) is a micro system based on integrated circuit process design and manufacture. As an important component of MEMS, micromixers have been paid more and more attention, and the study of micro-scale flow and liquid mixing has become more and more important. The research methods of physical system can be divided into three categories: theoretical research, experimental research and numerical simulation. With the rapid development of computer technology, numerical simulation technology has been paid more and more attention and widely used. As a new mesoscopic simulation method, lattice Boltzmann method has been developed rapidly in the past 20 years. LBM can not only analyze the non-continuous flow field, but also make important progress in simulating microfluid flow and modeling. In this paper, the fluid mixing problem in micro mixer is simulated based on LBM. Firstly, the basic theory of LBM is introduced, the Boltzmann equation is deduced in detail, and some basic models and boundary treatment methods of LBM are introduced. Then, the feasibility and accuracy of LBM are verified by the simulation of three typical examples in fluid mechanics, and the mixing index 蟽-is introduced to evaluate the mixing effect. Finally, the LBM is applied to the fluid mixing simulation of the micro mixer, and the numerical simulation of the simple T type micro mixer and the inner rib type micro mixer is carried out, and the influence curves of different factors on the mixing effect are obtained. For a simple T-type micromixer, the following conclusions are obtained: the smaller the inlet velocity, the better the mixing effect; the smaller the mixing channel width, the better the mixing effect, but the smaller the mixing exponent is, the faster the fluid diffuses, the greater the collision coefficient, the faster the fluid diffusion. The better the mixing effect is, the worse the mixing effect is with the increase of viscosity coefficient. For the inner ribbed micro mixer, the mixing effect of the fluid varies first and then better with the decrease of the inlet velocity, and the collision coefficient has little effect on the mixing at high speed and obvious effect on the mixing at low speed. The greater the length of the inner rib plate, the better the mixing effect of the fluid, and the worse the mixing effect of the fluid is with the increase of the period length, but the change of the mixing index is not great. Finally, the mixing performance of the two micromixers at different inlet velocities is compared. The inner rib micromixers are much better than the simple T-type micromixers.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH-39

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