Experimental and numerical study of gas flow through microchannel with 90° bends

Abstract A microchannel with a 90° bend is one of the essential components of a complex microchannel in microdevices. Therefore, a fundamental understanding of flow through a microchannel with bends is required. This paper investigates gaseous flow experimentally and numerically through a microchannel with bends in the slip regime. A microdevice with 20 microchannels of dimensions 393.96 × 1.03 × 25 200 µ m 3 with double 90° bends has been fabricated using standard silicon microfabrication processes. These channels have a common inlet and outlet plenum, and nitrogen gas is used as the working fluid. The mass flow rate through the microchannel is measured for various pressure ratios ranging between 1.30 and 1.55 at different outlet Knudsen numbers in the slip regime. Three-dimensional simulations are performed for rarefied isothermal flow using Ansys fluent 18.1 with slip boundary conditions on the top and bottom walls. The slip effect is quantified by comparing the measured data of the mass flow rates with the corresponding no-slip boundary conditions. To the authors’ best knowledge, experimental data in the slip regime covering the Knudsen number range 0.0662–0.0805 have not been reported previously. The gas flow was modelled numerically using the first-order model with an appropriate slip coefficient ( C 1 = 1.15), and the equivalent straight length per bend in the slip regime was also calculated.