The influence of surface roughness on nanoscale radiative heat flux between two objects

•The roughness effect on micro/nano-scale thermal radiation is studied.•Roughness factor is calculated by combining the FDTD and WCE methods.•Thermal radiation increases with increase in the root mean square height.•A smaller correlation length enhances thermal radiation.

Radiative heat transfer between two closely located plates can exceed black body limit due to the near-field effects. The surface roughness is not considered in the investigation of the enhancement of the near-field radiative heat transfer. In this paper, a computational model based on the finite-difference time-domain (FDTD) method and the Wiener Chaos Expansion (WCE) method is established to calculate the near-field radiative heat transfer between two plates with Gaussian type rough surfaces. The effect of the surface roughness on the near-field radiative heat transfer is analyzed. The numerical results show that the surface roughness has an obvious impact on the spectral radiative heat flux between two plates and the near-field radiative heat transfer may be decreased by the very small surface roughness. This indicates that the surface roughness needs to be considered in order to precisely evaluate the near-field radiative heat transfer between two plates.