  We present a particle method for estimating the curvature of interfaces in
volume-of-fluid simulations of multiphase flows. The method is well suited for
under-resolved interfaces, and it is shown to be more accurate than the
parabolic fitting that is employed in such cases. The curvature is computed
from the equilibrium positions of particles constrained to circular arcs and
attracted to the interface. The proposed particle method is combined with the
method of height functions at higher resolutions, and it is shown to outperform
the current combinations of height functions and parabolic fitting. The
algorithm is conceptually simple and straightforward to implement on new and
existing software frameworks for multiphase flow simulations thus enhancing
their capabilities in challenging flow problems. We evaluate the proposed
hybrid method on a number of two- and three-dimensional benchmark flow problems
and illustrate its capabilities on simulations of flows involving bubble
coalescence and turbulent multiphase flows.
