Micro Scale Air Sampling Devices: A Numerical Study

Numerical simulation of particle collection in a newly developed microfluidic air sampling device is presented in this study. In the simulations, the air carrying the particles is injected into a liquid column to form a bubble. The bubble then releases from the air inlet following with interface deformations and rises in the liquid column carrying the particles inside. During this bubbling process, the particles having impact with the bubble interface are collected in the extraction liquid. For the simulations, Navier-Stokes equations are solved along with piecewise-linear Volume-of-Fluid (VOF) method for tracking the interface deformations. The particle trajectories are predicted on a Lagrangian frame of reference by integrating the force balance on each particle. To validate the numerical model, the results for bubble terminal velocity and shape, and particle removal rate are compared with the available experimental data in the literature. Finally, particle removal from different bubble sizes is studied.