- Author
- Mulholland, G. W. | Mountain, R. D.
- Title
- Coupled Dipole Calculation of Extinction Coefficient and Polarization Ratio for Smoke Agglomerates.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Journal
- Combustion and Flame, Vol. 119, 56-68, 1999
- Keywords
- smoke | agglomerates | extinction
- Identifiers
- coupled dipole method; mass concentration; polarization ratio; specific extinction coefficient
- Abstract
- The mass specific extinction coefficient and the polarization ratio at 90 deg of simulated smoke agglomerates are computed for clusters with 3 to 1390 primary spheres and for size parameter from 0.05 to 0.6 using the coupled electric and magnetic dipole (CEMD) method. For the size parameter range of interest for post-flame smoke, the specific extinction coefficient computed by CEMD is 21% to 36% greater than Rayleigh prediction, and for this size range for clusters with 100 - 1,000 primary spheres, the range in the specific extinction coefficient is about 12%. Aggrement between measured and predicted specific extinction coefficient would require selection of a refractive index outside the range of values wiedly used by the combustion community. The polarization ratio at 90 deg is found to be a monotonic function of primary sphere size and relatively independent of agglormerate size. Comparison with the limited experimental resutls indicates potential for polarization ratio as a diagnostic for primary sphere size.