Hydrodynamic Entrance Length for Laminar Flow in Microchannels with Rectangular Cross Section

This work presents a detailed numerical investigation on the required development length (L=L/B) in laminar Newtonian fluid flow microchannels with rectangular cross section and different aspect ratios (AR). The advent of new microfluidic technologies shifted practical Reynolds numbers (Re) to range unitary (and even lower) orders magnitude, i.e., creeping conditions. Therefore, accurate estimations L at Re?O(1) are important for microsystem design. At such low numbers, which inertial forces less dominant than viscous forces, characteristics become necessarily from those macroscale where Re is typically much larger. A judicious choice mesh refinement adequate methods allowed obtaining results general correlation estimating L, valid ranges 0?Re?2000 0.1?AR?1, thus covering applications both macro microfluidics.