用PIV和LBM法检验灌水器设计中连续介质假设的适用性  

Applicability on continuous medium hypothesis in design of emitter using PIV and LBM method

作　　者：马胜利[1] 魏正英[1] 张育斌[1] 陈雪丽[1] 马超[1] 

机构地区：[1]西安交通大学机械工程学院机械制造系统国家重点实验室,西安710049

出　　处：《农业工程学报》2017年第9期92-98,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家科技支撑计划项目(2015BAD24B01);国家重点研发计划项目(2016YFC0400201)

摘　　要：灌水器由于其流道特征尺寸微小,因而在其流道内的流动特性分析中,基于连续性介质假设的Navier-Stokes(NS)方程是否适用一直存在争议。该文从微观角度采用格子Boltzmann方法(1attice Boltzmann method,LBM)研究灌水器的流动特性。首先进行LBM的网格无关性分析,其次将LBM的数值计算结果、传统的基于连续性介质假设下的有限体积法的计算流体动力学(computational fluid dynamics,CFD)计算结果以及粒子图像测速(particle image velocimetry,PIV)试验结果进行对比,分析LBM计算结果与基于CFD结果偏离PIV试验值的相对偏差的算术平均值。结果表明,CFD偏离PIV试验结果的相对偏差的算术平均值为0.139%,而LBM偏离PIV试验的相对偏差的算术平均值为0.115%,两者偏离PIV试验结果的相对偏差的算术平均值比较接近。因此,针对流道特征尺寸为1 mm的灌水器,采用基于连续性介质假设下的流体动力学计算方法来研究是适用的。The characteristics of microfluidic devices are different from those of ordinary fluid devices, One of the most important features of microfluidic devices is the decrease of their characteristic scale. This feature leads to a lot of differences in microfluidic device. Two major differences are included. There are the flow law of the fluid and the physical properties of fluid. The flow law of the fluid in a microfluidic device is different from that in an ordinary fluid device. The physical properties of the fluid in a microfluidic device also differ from that in an ordinary fluid device. The emitter channel is small in size from the point view of its width. As a result, the emitter belongs to the microfluidic device. Therefore, the applicability of Navier-Stokes （NS） equations has been controversial in the analysis of the flow characteristics in the emitter channel. In order to verify the suitability of the continuity medium hypothesis in design of the emitter, the lattice Boltzmann method （LBM） was used to study the flow characteristics of the emitter in this paper. The flow rate field on a specific plane obtained by different numerical methods was analyzed. The numerical methods were LBM and the computational fluid dynamics （CFD） method which was based on the finite volume method. The flow rate field obtained by using the two numerical methods was also compared with the experimental results. The flow rate with larger flow rate gradient of the straight line on the specific plane was also compared and analyzed. Firstly, the mesh independent analysis was made in order to guarantee the numerical accuracy of numerical results. Secondly, the numerical results were compared with those obtained by the finite volume method （FVM） based on the assumption of continuous medium. The numerical results were also made a comparison with the particle image velocimetry （PIV） experimental results. The average relative deviations of the results of the LBM calculation from the experimental values of PIV were analy

关 键 词：CFD BOLTZMANN方程 流速 PIV 连续介质假设 LBM 灌水器 

分 类 号：S275.6[农业科学—农业水土工程]