  We study the near-field radiative heat transfer between two twisted
finite-size polar dielectric nanoparticle gratings. Differently from previous
studies of the same configuration, we do not rely on any approximated effective
medium theory to describe the gratings. By the full many-body radiative heat
transfer theory we are able to investigate how the size, distance and relative
orientation between the gratings influence the radiative heat flux. By changing
the twisting angle $\theta$, we show a significant oscillation of the thermal
conductance $G(\theta)$, due to the size effect for gratings of both square and
circular shapes. The distance- and twisting-dependent coupling between the
gratings accounts for a strong and characteristic modulation of radiative
thermal conductance with implications for the energy management, sensing, and
NEMS/MEMS devices.
