Abstract
Developing a three-dimensional laminar flow in the entrance region of rectangular microchannels has been investigated in this paper. When the hydrodynamic development length is the same magnitude as the microchannel length, entrance effects have to be taken into account, especially in relatively short ducts. Simultaneously, there are a variety of non-continuum or rarefaction effects, such as velocity slip and temperature jump. The available data in the literature appearing on this issue is quite limited, the available study is the semi-theoretical approximate model to predict pressure drop of developing slip flow in rectangular microchannels with different aspect ratios. In this paper, we apply the lattice Boltzmann equation method (LBE) to investigate the developing slip flow through a rectangular microchannel. The effects of the Reynolds number (1 < Re < 1000), channel aspect ratio (0 < ε < 1), and Knudsen number (0.001 < Kn < 0.1) on the dimensionless hydrodynamic entrance length, and the apparent friction factor, and Reynolds number product, are examined in detail. The numerical solution of LBM can recover excellent agreement with the available data in the literature, which proves its accuracy in capturing fundamental fluid characteristics in the slip-flow regime.
Highlights
In recent years, rapid development in manufacturing technologies, together with a motivation toward micro-electrical mechanical system (MEMS) [1,2,3,4], have attracted much academic research of laminar flows in relatively short channels with different cross-sections
The results indicated that the lattice Boltzmann method (LBM) can provide computational guidance to the design of catalytic devices operating the pulsed conditions at high Knudsen numbers (0.1 < Kn < 1)
We have performed an investigation in slip flow through a rectangular microchannel using an improved incompressible LBGK D3Q15 model
Summary
Rapid development in manufacturing technologies, together with a motivation toward MEMS [1,2,3,4], have attracted much academic research of laminar flows in relatively short channels with different cross-sections. We pay special attention on the slip flow, where the rarefaction effect may be significant, and the conventional Navier–Stokes simulation can be used with appropriate s velocity slip boundary conditions. This regime has attracted extensive attention from the engineering research community because of its significance associated with many of the practical microfluidic devices. It has been the subject of many studies employing continuum modeling to examine the slip-flow convection at the microscale [5,6,7,8] over the past two decades
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