A new efficient numerical model of particle scale radiation is developed.
The paper is "Wu, H., Gui, N., Yang, X., Tu, J., & Jiang, S. (2018). Particle-scale investigation of thermal radiation in nuclear packed pebble beds. Journal of Heat Transfer, 140(9), 092002."
And the link is http://heattransfer.asmedigitalcollection.asme.org/article.aspx?articlei...
It is a compromise between the computational time and the level of detail.
More discussion or suggestions are welcomed.