Numerical Analysis on the Radiant Characteristics of Three-Dimensional Random Rough Surfaces

In the area of micro- and nano-scale radiation heat transfer, the radiant characteristics of rough surfaces have drawn increasing attention. In this paper, three-dimensional Gaussian random rough surfaces were created by the Monte Carlo simulation method. Ray tracing method combined with the Kirchhoff approximation was employed to analyze the shadowing effect of random surfaces with different roughness. The relative scattering intensity from rough surfaces was further investigated by the Fresnel law. The results indicated that the peak of the relative scattering intensity occurred at the anti-scattering angle and the scattering distributions were continuous. With increasing surface roughness, the height of the peak became lower, the width of distribution became wider, and the distribution range of the scattering angle and the azimuth of the reflection electromagnetic waves increased. Furthermore, the relative scattering intensity concentrated in the vicinity of the anti-scattering angle and the largest scattering intensity occurred in the specular direction. Taking into account of the effects of polarization state and wavelength of incidence waves, it was shown that the relative scattering intensity of s polarized incident wave was slightly larger than that of p polarization, while the relative scattering intensity became stronger as the wavelength increased.