Effects of geometry on simulation of two-phase flow in microchannel with density and viscosity contrast

With respect to the importance of a multiphase flow behaviour in a microchannel, this study is focused on developing a numerical modelling of two-phase flows using lattice Boltzmann method (LBM). This method utilizes a different vision for surveying the behaviour of fluids. The LBM be able to capture fluid motion via a microscopic vision in contrary to classical CFD methods (Navier–Stokes approach). Based on this capability, the LBM is a powerful method for solving complex problems in multiphase and multicomponent fluid dynamics problems. This research attempts to employ the chromo-dynamic model, which is compatible for high-density ratio flow in a microchannel and introduces different approaches to achieve this objective. This study examined both Huang and Lishchuk methods and the obtained results show a sharp interface between two phases by using Haung model. However, utilization of this method can impose some difficulties on stability of calculation. The research tries to eliminate or at least weaken numerical errors caused by density contrast in the interface of different phases from the exertion of an artificial force. A numerical modelling approach comprises an accurate treatment of the surface tension between phases and a passive-scalar heat transfer method. This research used a high-performance simulation to obtain real-time flow visualizations. The proposed method is applied to a new geometry with variable cross section. A correlation introduced between this geometry and dimensionless numbers (Bejan number, Laplace number, Reynolds number). This new correlation defines an operational criterion for a step-contracted microchannel and enables us to capture the delay time between fluctuations. The results are compared to available exact solutions for high-density ratio flow in a microchannel.