  In this paper, we present a simple and accurate lattice Boltzmann (LB) model
for immiscible two-phase flows, which is able to deal with large density
contrasts. This model utilizes two LB equations, one of which is used to solve
the conservative Allen-Cahn equation, and the other is adopted to solve the
incompressible Navier-Stokes equations. A novel forcing distribution function
is elaborately designed in the LB equation for the Navier-Stokes equations,
which make it much simpler than the existing LB models. In addition, the
proposed model can achieve superior numerical accuracy compared with previous
Allen-Cahn type of LB models. Several benchmark two-phase problems, including
static droplet, layered Poiseuille flow, and Spinodal decomposition are
simulated to validate the present LB model. It is found that the present model
can achieve relatively small spurious velocities in the LB community, and the
obtained numerical results also show good agreement with the analytical
solutions or some available results. At last, we use the present model to
investigate the droplet impact on a thin liquid film with a large density ratio
of 1000 and the Reynolds number ranging from 20 to 500. The fascinating
phenomenon of droplet splashing is successfully reproduced by the present model
and the numerically predicted spreading radius exhibits to obey the power law
reported in the literature.
