Dynamic flow characteristics in U-type anti-high overload microfluidic inertial switch

Abstract

Under the action of unidirectional inertial force, the working liquid can bear high overload and not be dispersed in the U-type connected microchannel. This structure provides the possibility for designing anti-high overload microfluidic inertial switch. Based on the designed U-type microfluidic inertial switch, the dynamic flow process of liquid in U-type microchannel under inertial force was studied to predict and evaluate the characteristic of anti-overload. The unsteady Bernoulli flow model with the effect of viscosity local resistance was derived by utilizing the undetermined factor k. The VOF and CSD modules in CFD software were employed to analyze the transient flow process, and then the factor k was obtained by the simulation results. Centrifugal test platform was utilized to measure the variation of liquid surface movement displacement. The result shows that the modified dynamic flow model can reasonably describe the flow process of liquid surface, and the oscillations frequency and amplitude of the liquid surface increase with the increase of the inertial acceleration and the cross-sectional size of the microchannel. Moreover, even under the load of 3000 g, the liquid does not appear to be dispersed, which indicates that the U-type structure inertial switch has the characteristics of anti-high overload.