PARAM, SIGMA

Bulk Data Entry The Stefan-Boltzmann constant used in Radiation Heat Transfer calculations.

Parameter	Values	Description
`SIGMA`	< Real > Default = 0.0	The radiation heat flux is:(1) $q = σ \cdot FAMB \cdot (ε_{e} {(T_{e} + T_{a b s})}^{4} - α_{e} {(T_{a m b} + T_{a b s})}^{4})$ $q = σ \cdot FAMB \cdot (ε_{e} {(T_{e} + T_{a b s})}^{4} - α_{e} {(T_{a m b} + T_{a b s})}^{4})$ Where, $σ$ $σ$ Stefan-Boltzmann constant (PARAM,SIGMA). $q$ $q$ Radiation heat flux. $FAMB$ $FAMB$ Radiation view factor between the element face and the ambient space node. This is defined on the RADBC entry. $ε_{e}$ $ε_{e}$ Surface emissivity of the surface element, defined by `EMIS1` on the RADM entry. $α_{e}$ $α_{e}$ Surface absorptivity of the surface element, defined by `ABSORP` field on the RADM entry. $T_{e}$ $T_{e}$ Surface temperature. $T_{a b s}$ $T_{a b s}$ Absolute temperature scale defined via PARAM, TABS. $T_{a m b}$ $T_{a m b}$ Ambient temperature. The temperatures and SIGMA should be defined in consistent units. Based on the input temperature units, the absolute temperature scale, $T_{a b s}$ $T_{a b s}$ , can be defined via PARAM,TABS. The value of SIGMA in SI units is 5.67E-8 Watts/m²K⁴.

Comments

If PARAM, SIGMA is not set, there is no heat transfer based on radiation in the model.