Convergence analysis of the thermal discrete dipole approximation
Abstract
The thermal discrete dipole approximation (TDDA) is a numerical approach for modeling nearfield radiative heat transfer in complex threedimensional geometries. In this work, the convergence of the TDDA is investigated by comparison against the exact results for two spheres separated by a vacuum gap. The error associated with the TDDA is reported for various sphere sizes, refractive indices, and vacuum gap thicknesses. The results reveal that for a fixed number of subvolumes, the accuracy of the TDDA degrades as the refractive index and the sphere diameter to gap ratio increase. A converging trend is observed as the number of subvolumes increases. The large computational requirements associated with increasing the number of subvolumes, and the shape error induced by large sphere diameter to gap ratios, are mitigated by using a nonuniform discretization scheme. Nonuniform discretization is shown to significantly accelerate the convergence of the TDDA, and is thus recommended for nearfield thermal radiation simulations. Errors less than 5% are obtained in 74% of the cases studied by using up to 82 712 subvolumes. Additionally, the convergence analysis demonstrates that the TDDA is very accurate when dealing with surface polariton resonant modes dominating radiative heat transfer in the near field.
 Publication:

Physical Review E
 Pub Date:
 June 2015
 DOI:
 10.1103/PhysRevE.91.063307
 arXiv:
 arXiv:1502.02186
 Bibcode:
 2015PhRvE..91f3307E
 Keywords:

 02.70.c;
 44.40.+a;
 42.25.Bs;
 Computational techniques;
 simulations;
 Thermal radiation;
 Wave propagation transmission and absorption;
 Physics  Computational Physics
 EPrint:
 46 pages, 12 figures, 3 tables