A novel Approach to Calculate Radiative Thermal Exchange in Coupled Particle Simulations

We present a novel algorithm to calculate radiative energy transfer rates in Discrete Element Method
(DEM)-based simulations of mono-disperse spheres. To verify our algorithm we use the Finite
Volume Method (FVM) which enables us to picture relevant radiation phenomena in a dense bed of
particles. These phenomena include (i) shadowing, (ii) emission and (iii) adsorption by a constant
grey medium. After careful verification, we embed our algorithm in LIGGGHTS, a solver for the DEM.
A combination of LIGGGHTS and a solver for intra-particle temperature gradients, i.e., ParScale,
is then used to quantify the relevance of radiative heat transfer rates in sheared particles beds.
Specifically, we evaluate the relative contributions of conductive, convective and radiative thermal
fluxes in granular shear flows of frictional inelastic spheres. We find that that the radiative flux can
be collapsed onto single curve if it is related to an appropriate dimensionless group. Our analysis
establishes a rationale on when radiative heat transfer in dense granular flows should be considered
or not. Also, our results can be used to close continuum-based granular dynamics model that aim
on predicting the particle temperature distribution under extreme temperature scenarios.