微流控芯片通道结构的拓扑优化研究

摘要

In order to study the influence of non-Newtonian fluid viscous effect on the channel structure design and layout of microfluidic chips in topology optimization,an optimal topology design is proposed for the "double-in-one-out" microchannel structure with different flow length design domains.The topological optimization of the microfluidic structure for Newtonian fluid and non-Newtonian fluid is carried out by density method.The effects on topological structure of two different objective functions,including pressure drop function and energy dissipation function are analyzed.The optimal structure and viscosity distribution under different conditions are compared.For non-Newtonian fluid,an improved cross viscosity model is used.The results show that the viscous effect of non-Newtonian fluid is independent of the convergence point of the inlet double pipes and the length of the flow channel at Re=0.1 (Stokes flow) when the objective function is pressure drop.The optimal topology of non-Newtonian fluid is similar to that of Newtonian fluid at Re=100 (Navier-Stokes flow) and the confluence point of inlet pipes is moved backwards with the increase of channel length.When the minimum energy dissipation is set as the objective,the viscous effect of non-Newtonian fluid at Re=0.1 shows that the flow inlet angle decreases with the increase of channel length.In the optimal topology of Newtonian fluid,the outlets of the design field are double-pipe outflows,in which there is no convergence point in the short pipe and square pipe.In the long tube,double inlet tubes are merged into a single tube and then split to form an oval ring structure.%为了研究拓扑优化过程中非牛顿流体黏性效应对微流控芯片通道结构设计及布局的影响,针对不同流动长度设计域的“两进一出”型微通道结构,提出了拓扑结构最优设计的新思路.采用密度法分别对牛顿流体和非牛顿流体进行微流动结构拓扑优化,分析了以压力降函数和能量耗散函数这2种不同目标函数对拓扑结构的影响,比较了各个条件下的最优结构和黏性分布.对于非牛顿流体,采用改进的Cross黏性模型进行计算,结果表明:当目标函数为压力降时,非牛顿流体黏性效应在雷诺数Re为0.1(Stokes流动)时表现为进口双管的汇合点与流道长度无关,在Re为100(Navier-Stokes流动)时,非牛顿流体与牛顿流体的最优拓扑结构相似,进口管的汇合点都随着通道长度的增加而后延;当目标为最小能量耗散时,非牛顿流体黏性效应在Re为0.1时表现为流动进口角度随流道长度增加而减小,而在牛顿流体最优拓扑结构中,设计域出口处均为双管流出,其中在短管和方管中没有出现汇合点,在长管中进口双管汇合为单管后又分流形成椭圆环状结构.