Characterizing Dynamic Contact Angle during Gas-Liquid Imbibition in Microchannels by Lattice Boltzmann Method Modeling.

Spontaneous imbibition in microchannels is a critical phenomenon in various industrial applications, such as enhanced oil recovery and microfluidic systems. One of the key factors influencing the imbibition process is the dynamic wetting effect, which governs the interaction between the liquid and solid surfaces. This paper improves the original pseudopotential model for interfluid forces by coupling it with the Peng-Robinson equation of state. The model's accuracy is verified through thermodynamic consistency checks, simulations of gas-liquid interfacial tensions, and testing of static equilibrium contact angles. Following model validation, we use it to simulate spontaneous gas-liquid imbibition in microchannels and investigate dynamic contact angle evolution during the process. The results demonstrate that (1) as the microchannel width increases, inertia forces become more significant during the initial imbibition stages, leading to a greater difference between the dynamic and static contact angles. (2) A decrease in fluid-solid interaction strength results in a larger gap between dynamic and static contact angles. (3) Higher interfacial tension strengthens the capillary forces, accelerating the imbibition rate and enlarging the difference between the dynamic and static contact angles. Furthermore, the dynamic contact angle data obtained from our simulations can be used to correct the traditional Lucas-Washburn equation. The corrected equation predicts imbibition distances that closely match the simulation results.