  Van der Waals heterostructures have exhibited interesting physical
properties. In this paper, heat transfer in hybrid coplanar bilayer/monolayer
(BL-ML) graphene, as a model layered van der Waals heterostructure, was studied
using non-equilibrium molecular dynamics (MD) simulations. Temperature profile
and inter- and intra-layer heat fluxes of the BL-ML graphene indicated that,
there is no fully developed thermal equilibrium between layers and the drop in
average temperature profile at the step-like BL-ML interface is not
attributable to the effect of Kapitza resistance. By increasing the length of
the system up to 1 $\mu$m in the studied MD simulations, the thermally
non-equilibrium region was reduced to a small area near the step-like
interface. All MD results were compared to a continuum model and a good match
was observed between the two approaches. Our results provide a useful
understanding of heat transfer in nano- and micro-scale layered 2D materials
and van der Waals heterostructures.
