Lattice Boltzmann simulations of liquid flows in microchannel with an improved slip boundary condition

Flow characteristics in channels are critical in chemical engineering. Slip velocity has a great influence on the microchannel flows. The lattice Boltzmann simulations of some typical channel flows are conducted with an improved slip boundary condition. Through theoretical analysis, the defects of the existing slip boundary conditions are clarified. To solve these problems, the slip boundary condition of Kuo et al. is ameliorated by considering the tangential momentum change generated by the external force. Besides, the Navier's slip model is adopted to specify the improved slip boundary condition. With this improved scheme, we study five cases, namely the Couette flow, the force driven Poiseuille flow, the time-dependent force driven Womersley flow, the porous plate flow and the channel flow with a surface-mounted block. Our method is accurate and reliable enough even with a coarse grid. The mass leakage at the wall is avoided and the numerical error generated by the external force is eliminated. (C) 2019 Elsevier Ltd. All rights reserved.