Reynolds-Number Effect on the Flow Structure in a Deterministic Lateral Displacement (DLD) Microfluidic Chip

This study presents a comprehensive experimental and numerical investigation into the effects of Reynolds number (Re) on flow behavior in deterministic lateral displacement (DLD) devices. While conventional DLD operation typically occurs at low Reynolds numbers (Re < 1) where viscous forces dominate, this research systematically explores the transition to higher Re regimes (0.04 Re 66.7) to address the critical need for increased throughput in practical applications. The results demonstrate that increasing Reynolds number significantly alters flow profiles, with the emergence of recirculating vortices behind posts at Re ≈ 50 and notable streamline narrowing, both factors reducing the effective critical diameter ( Dc ) for particle separation. These findings reveal the limitations of traditional Dc models, which remain accurate only in the low Re regime prior to vortex formation.