A geometrical mass control loop is proposed in this research to use in the level set method in order to simulation of multiphase flows with complex topologies of the interface and a case study is investigated using proposed scheme. In this regard oblique interaction and coalescence of bubbles in a liquid is investigated. The level set method is suffering from poor mass conservation in the case of severe changes of interface and complex topologies encountered in a wide range of problems which one of them is oblique coalescence of the bubbles. Despite the use of full re-initialization and reconstruction approach of the level set method as well as application of fine mesh, deviation of mass conservation of the method even becomes 100%. Therefore, simulation of such problems sometimes becomes impossible using this method. So in the geometric mass control loop, mass deviation in each time step is calculated and is compensated in the dispersed phase, which prevents the propagation of mass error entire the simulation. Efficiency of proposed geometrical mass control loop is verified by simulation of oblique interaction and coalescence of gas bubbles in a liquid. The governing equations are continuity and momentum equations which have been discretized using the finite volume method and the SIMPLE algorithm. The results outlined in the present study well agree with the existing experimental and numerical results. Results show that the maximum amount of mass dissipation was less than 4%. Therefore, the level set method with proposed geometric mass control loop could be used properly for the simulation of multiphase flows with sharp and high variations in the interface.
A semi-implicit level set method for multiphase flows and fluid–structure interaction problems
