Sweeping of the entrapped fluid out of the groove in a three-dimensional channel using lattice Boltzmann method

Abstract

The entrapment of fluid inside a groove is an important topic of research from past few decades. In many engineering applications, it is seen that the droplet is displaced under the action of gravitational force on one of the wetted grooved wall of a rectangular three-dimensional channel. It is reported in literature that the entrapment of droplet fluid inside groove is undesirable in various applications. Thus, the present study deals with the method of sweeping out the entrapped fluid inside the groove by the displacement of a large size three-dimensional immiscible droplet under gravity. To analyze this problem, a three-dimensional lattice Boltzmann method (LBM) is used and Shan–Chen (S-C) model has been implemented to incorporate multiphase-multicomponent flow. The present problem deals with the single grooved wetted wall of a rectangular three-dimensional channel. The wettability of the groove surface is considered as uniform hydrophobic in two different cases, whereas the wettability of the three-dimensional channel wall outside of the groove is considered as uniform hydrophilic. The analysis shows that the sweeping of entrapped fluid out of the groove largely depends on the capillary number and groove dimensions. It is also observed that sweeping of entrapped fluid takes place only for uniform hydrophobic surface of the groove with contact angle equal to 118°. In case of hydrophobic surface with contact angle equal to 90°, the large size droplet completely trapped inside the groove and does not able to sweep out the previously entrapped fluid.