Atomistic evidence of hydrodynamic heat transfer in nanowires

•The radial heat flux distribution in silicon nanowires has a Poiseuille-like shape.•The addition of an amorphous shell decrease the heat flux in the center.•The heat flux at the interface is not affected by the presence of a shell.•The radial distribution can be fitted using the hydrodynamic heat equation.•The effect of the shell is modeled by changing the thermal conductivity.