A Numerical Investigation of Thermal Radiation Scattering From Configured and Random Surfaces

Thermal radiation scattering from one-dimensional and two-dimensional surfaces are presented. The surface profiles are configured or random rough with geometrical scales on the order of the wavelength. Scattered energy distributions from one-dimensional surfaces are restricted within the incidence plane while scattered energy from two-dimensional surfaces is distributed in the entire hemisphere. The bi-directional reflection function and the directional hemispherical reflectivity are calculated for one- and two-dimensional surfaces and the directional emissivities are also reported for one-dimensional surfaces. For one-dimensional surfaces with a single-length scale, the dominant parameter affecting the directional emissivity and the hemispherical emissivity is found to be the slope of the surface, expressed as the ratio of surface height over surface geometrical correlation length. When a one-dimensional surface is composed of two substructures with different length scales, the substructure with larger slope prescribes the radiative properties of the surface. Modal scattering phenomena are observed for two-dimensional configured surfaces in different scattering planes. The scattering directions of scattered energy peaks are prescribed by the ratio of the surface geometrical correlation length and wavelength. Specular scattering diminishes with increasing surface heights, and the scattered energy in the specular scattering direction competes with other non-specular scattered energy when the incidence is oblique. A continuous reflection distribution is observed for two-dimensional random rough surfaces. Scattered energy distributions are found to concentrate around the specular scattering directions for the random rough surfaces considered and similar directional emissivities are also observed for such random surfaces.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Nuclear Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Yang, Yongqing

Contributors dc:contributor

• Buckius, Richard O.

• Engineering, Mechanical

Language dc:language

eng

Identifier

(MiAaPQ)AAI9912432

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/85944