惯性微流体开关阈值特性与响应历程的数值仿真

根据变矩形截面微通道惯性微流体开关的结构和工作机理,建立了水银液滴在临界状态下的开关静态阈值模型。采用VOF模型,考虑了表面张力作用和接触角效应,模拟了水银液滴在微通道中的动态时间历程,较准确地反映了液滴形状连续变化中的关键特征。通过对水银液滴速度随时间变化的跟踪,验证了开关具有阈值特性。仿真分析了微阀门宽度、微通道深度等结构参数对加速度阈值的影响,从而验证了阈值解析公式。当接触角为130°至170°时,数值仿真结果显示开关的响应时间随着接触角的增大而减小。讨论了不同网格尺寸对开关动态过程仿真计算结果的影响,结果曲线表明在仿真设置条件下计算结果对网格尺寸依赖较小。

Numerical Simulation on Threshold Characteristics and Response Process of Micro-fluidic Inertial Switch

According to structure and mechanism of micro-fluidic inertial switch with varying rectangular cross-section,the static model of threshold g-value in critical state is established.Based on the VOF with containing surface tension and contact angle effects,the transient response process of mercury droplet in the microchannel is simulated using Fluent,which reflects the key feature of droplet deformation.By tracing the droplet velocity during the response time,threshold characteristics is illustrated by numerical simulation.The analytic equation is verified by simulating the influence of design parameters of microchannel on threshold g-value.The simulation analysis on the dynamic behavior of the switch shows that the response time decreases slightly with the increase of the contact angle when the contact angle is within the range of 130°～170°.In addition,the dynamic process of inertial switch is simulated for three different grid sizes,and the result indicates that there is no significant variation in results as the grid resolution is changed.