Study of vortex breakdown in immiscible media using the lattice Boltzmann equations method

Numerical simulation is performed for a cylinder-bound two-component liquid flow. Simulation model is based on the method of lattice Boltzmann equations. The collision integral in this model is defined from the MRT approximation. The interaction between liquid components is described by the diffusion interface model with the pseudopotential approximation. The main deficiency of this known approach is the disbalance of discrete forces of two-component interaction; this would generate a pseudo-current in the transition zone. The presented numerical study offers a qualitative view for the pseudopotential function providing a smallest value for intercomponent interaction coefficient. This means the low pseudo-currents and the smallest size for the diffusive transition. The example simulation is presented for a problem of rotation of two components in a cylinder. The simulation gives also the Reynolds number range and the cylinder aspect ratio that ensure the start of flow recirculation at the cylinder axis. It was demonstrated that simulation results comply with experimental data with a high accuracy.