Effects of particle size, particle density and Reynolds number on equilibrium streaks forming in a square wave serpentine microchannel: A DEM-LBM simulation study including experimental validation of the numerical framework

Classical fractionation principles are often not suited for microparticles. Therefore methods specifically designed to fractionate in those size ranges are being developed. One approach is the fractionation in serpentine microchannels: It has so far been mainly used for size fractionation but seems to be suited for density fractionation as well. In order to optimally design the systems to fractionate for particle size and density, detailed information on their combined influence on the forming equilibrium streaks is needed. As this information is currently lacking, we study those effects using a coupled DEM-LBM simulation approach. We include a detailed analysis of equilibria over the periodic elements of the channel structure, which is important for optimal placement of the channel outlet. The results confirm the capability of serpentine channels for density fractionation and demonstrate that density dependency is greatest at elevated Reynolds numbers and in channel sections orthogonal to the main channel orientation.