  We study the radiative heat flux between two nanoparticles in close vicinity
to the natural hyperbolic material hBN with its optical axis oriented parallel
to the interface. We show that the heat flux between the nanoparticles can be
efficiently modulated when rotating the nanoparticles due to the coupling to
the highly directional hyperbolic surface modes in hBN. Finally, we discuss the
thickness and distance dependence of this effect.
