LATTICE-BOLTZMANN ANALYSIS OF CAPILLARY RISE

The current study presents an investigation of capillary flow by using the two-phase lattice-Boltzmann method. The Shan-Chen single-component multiphase model was applied to simulate capillary rise in straight and sinusoidal capillaries. In order to validate our code, three test cases are considered: (a) The Laplace law is tested for various droplets, (b) the contact angle was verified by comparing the ratio of droplet wet length to droplet height at various adhesion parameters and (c) the verification of the Washburn equation for long times. The density distribution was presented for different geometry configurations and liquid front position was plotted as a function of time. The numerical results showed that the Washburn equation is not valid for short times. The internal structure of the flow inside the capillaries was described, thus the analysis shows the forming of recirculation zones near the inlet region and a decelerating effect of the varying path on the meniscus movement. For sinusoidal capillaries, we notice that the meniscus reaches different equilibrium positions.