UCLA

In many materials processing and manufacturing situations such as steel, aluminum, ceramics and glass, gas bubbles can form in liquid and solid phases. The presence of such bubbles affects the thermophysical properties and radiation characteristics of the two-phase system and hence the transport phenomena. This paper presents a general formulation of the radiation characteristics of semitransparent media containing large gas bubbles (bubble radius is much larger than the wavelength of radiation). Sample calculations for the spectral absorption and extinction coefficients and single scattering albedo of soda-lime silicate glass containing bubbles are discussed. Particular attention is paid to the effect of the volumetric void fraction and the bubble size distribution. Results clearly show that the presence of bubbles strongly affects the radiation characteristics of the semitransparent media containing entrapped gas bubbles, particularly if bubbles, void fractions, and spectral absorption coefficient of the continuous phase are small.