Definitions
• View Factor Fij—Fraction of radiation which leaves surface i and strikes surface j. You can calculate view factors between opaque surfaces in the solution domain using ray tracing.
• Rays—In radiative heat transfer, rays along a selected number of discrete directions are used to determine the view factors for the Surface to Surface (S2S) modelling. The default number of rays used is 256.
• Grain Size—Size of the cell face groups used to determine view factors. Default grain size = 1, which corresponds to view factors being calculated for every opaque cell face.
• Radiation—Boundary condition which accounts for the heat gained or lost based on the incident radiation, the temperature of the boundary, and the emissivity according to the following formula:
where,
 | Heat flux W/m2 |
ε | Emissivity |
σ | Stefan-Boltzmann constant = 5.67 x 10-8W/(m2-K4) |
T | Boundary temperature K |
A | Area of the boundary m2 |
• Emissivity—Ratio of the emitted radiative heat transfer to the incident radiative heat transfer.
• Reflective Boundary—An emissivity of zero would be equivalent to a totally reflective boundary, where no energy is absorbed due to the incident radiation.
• Absorbing Boundary—An emissivity of 1 would be equivalent to a fully absorbing boundary.