Y型微通道中压力驱动幂律流的流动分离

Flow separation of the pressure driven power-law flow in Y-shaped microchannel

基于Poisson-Boltzmann方程、修正的Cauchy动量方程和流体连续性方程,对压力驱动下的幂律流在Y型微通道中的流动过程进行了数值模拟。分析了不同的幂律指数、压强差下双电层电场、速度场的分布,以及双电层对速度场的影响。计算结果表明:(1)在Y型微通道的某些位置会发生流动分离(回流);(2)发生回流时的临界压强差和分叉角关系曲线表明:增大分叉角或降低幂律指数可使临界压强差下降;(3)幂律指数越小,双电层影响越明显;(4)增大压强差、降低幂律指数和增大分叉角度,均可使回流区域变大。

The pressure driven flow of power-law fluids in Y-shape microchannel is calculated by the fourth-order compact difference scheme.The governing equations are established by the complete Poisson-Boltzmann equation,modified Cauchy momentum equation and continuity equation.The distribution of the electric double layer potential,the pressure,the apparent viscosity and the velocity profiles of different parameters are obtained by the simulation.The results of the simulation are discussed.Furthermore,the effects of the electric double layer on the velocity profile were investigated.The results show that with the decrease of the power-law index,the velocity peak of the flow is larger in the microchannel,the effects of the electric double layer are more obvious.Compared the shear thickening and Newtonian fluids,the shear thinning fluids are much more sensitive to the other parameters.The recirculation generating conditions are studied.The recirculation generating critical pressure decrease with enlarging the branching angle or decreasing the power-law index.The pressure,the power-law index and the branching angle have significant influence on the flow separation when fixing the other parameters.Increasing the pressure,decreasing the power-law index or enlarging the branching angle also can extend the region of the flow separation.