(153g) A Numerical Study of Fluid Flow and Permeability in Directional Locking Pillar Arrays

The deterministic lateral displacement is a size based particle separation method, which is widely used for the separation and classification of microscale particles in the field of microfluidics. In this study, the effect of pillar diameter to gap size ratio on the fluid flow distribution and properties as well as theoretical particle separation cut point is researched. Furthermore, user-defined scalar (UDS) model in Fluent is used to study the extent of fluid (water) diffusion and permeability in different ordered pillar arrays for four different pillar shift fractions. Based on the obtained numerical results, a new model for prediction of the separation cut point, as a function of pillar diameter to gap size ratio and pillar shift fraction, is developed. It is found that the increase in pillar diameter to gap size ratio leads to the increase in separation cut point until the maximum cut point is reached. The permeability of the shifted pillar arrays investigated in this study is shown to be between the permeability of squared and hexagonal pillar arrays. Finally, it is found that the fluid diffusion is strongly affected by the pillar array arrangement and is proportional to the bulk permeability of the array.