  Local-to-Nonlocal (LtN) coupling refers to a class of methods aimed at
combining nonlocal and local modeling descriptions of a given system into a
unified coupled representation. This allows to consolidate the accuracy of
nonlocal models with the computational expediency of their local counterparts,
while often simultaneously removing additional nonlocal modeling issues such as
surface effects. The number and variety of proposed LtN coupling approaches
have significantly grown in recent year, yet the field of LtN coupling
continues to grow and still has open challenges. This review provides an
overview of the state-of-the-art of LtN coupling in the context of nonlocal
diffusion and nonlocal mechanics, specifically peridynamics. We present a
classification of LtN coupling methods and discuss common features and
challenges. The goal of this review is not to provide a preferred way to
address LtN coupling but to present a broad perspective of the field, which
would serve as guidance for practitioners in the selection of appropriate LtN
coupling methods based on the characteristics and needs of the problem under
consideration.
