| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 98 === In this work, the discrete ordinates method (DOM) and a modified discrete ordinates method (MDOM) have been applied to solve radiative transfer in a refractive rectangular medium exposed to a diffuse irradiation at one of its boundaries. The other boundaries are diffusely reflecting. The medium has a spatially varying refractive index and is assumed to be cold, absorbing and linearly anisotropically scattering. To develop the MDOM, we divide the intensity into the reduced incident intensity after partial extinction by absorption and out-scattering along the incident trajectory and a fairly diffuse part due to out-scattering by the medium. The reduced incident intensity in analytical form may be derived and the fairly diffuse part due to out-scattering is solved by the ordinary DOM. The computational results obtained by the DOM and the MDOM are compared with those obtained by the Monte Carlo method. The comparison of the results by these methods reveals that the solutions of optically thin cases obtained by the MDOM include less ray effects and so the MDOM is superior to the DOM. The direction-integrated intensity in the media and radiative heat flux at the boundaries are obtained for one- and two-dimensional distributions of refractive index, various optical sizes, scattering albedos, coefficients of scattering phase function and boundary reflectances. Refraction effects of the medium bend partial irradiation to the side boundary. Thus, in general, the radiative heat flux at the side boundary of the refractive medium considered is greater than that of the medium with a constant refractive index equal to the average of the refractive medium. Effects of other parameters on radiative transfer in refractive square media are also investigated.
|
|---|
