Investigation of Liquid Flow in Microchannels

Abstract

Liquid flow in microchannels is investigated both experimentally and numerically. The experiments are carried out in microchannels with hydraulic diameters from 244 to 974 µ ma tReynolds numbers ranging from 230 to 6500. The pressure drop in these microchannels is measured in situ and is also determined by correcting global measurements for inlet and exit losses. Onset of turbulence is verified by flow visualization. The experimental measurements of pressure drop are compared to numerical predictions. Results show that conventional theory may be used to predict successfully the flow behavior in microchannels in the range of dimensions considered here. Nomenclature Dh =h ydraulic diameter, µm f = Darcy friction factor H = microchannel height, µm L = microchannel length, mm l = characteristic size of eddies in turbulent flow, m P = pressure, Pa Q =v olume flow rate, m 3 /s Re =R eynolds number U =a verage velocity in microchannel, m/s u = characteristic velocity scale of eddies in turbulent flow, m/s W = microchannel width, µm x + = entrance length, mm α = aspect ratio, H/W � P = pressure difference, Pa δ = uncertainty e = dissipation rate, m 2 /s 3 η =K olmogorov length scale, m µ = fluid viscosity, N · s/m 2 ν = kinematic viscosity, m 2 /s ρ = fluid density, kg/m 3 app = apparent fd = fully developed conditions