Bulk Data Entry Defines the radiation material properties of a surface element for heat transfer analysis.

## Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

## Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

## Definitions

Field Contents SI Unit Example
RMID Radiation material property entry identification number.

No default (Integer > 0)

ABSORP Surface absortivity.

No default (0.0 ≤ Real ≤ 1.0)

EMIS1 Surface emissivity.

No default (0.0 ≤ Real ≤ 1.0)

1. The RADM entry can be referenced by a CHBDYE Bulk Data Entry.
2. The Radiation Heat Flux is calculated as follows, between the surface element and the black-body space node.(1)
$q=\sigma \cdot \text{FAMB}\cdot \left({\epsilon }_{e}{\left({T}_{e}+{T}_{abs}\right)}^{4}-{\alpha }_{e}{\left({T}_{amb}+{T}_{abs}\right)}^{4}\right)$
Where,
$q$
$\sigma$
Stefan-Boltzmann constant defined via PARAM, SIGMA.
$\text{FAMB}$
Radiation view factor between the element face and the ambient space node.
${\epsilon }_{e}$
Surface emissivity of the surface element, defined by EMIS1 on the RADM entry.
${\alpha }_{e}$
Surface absorptivity of the surface element, defined by ABSORP field on the RADM entry.
${T}_{e}$
Surface temperature.
${T}_{abs}$
Absolute temperature scale defined via PARAM, TABS.
${T}_{amb}$
Ambient temperature.
3. For a Heat Transfer Analysis via Radiation, PARAM,TABS can be used to define the absolute temperature scale, and PARAM,SIGMA is used to specify the Stefan-Boltzmann constant. Additionally, a RADBC entry can be used to define radiation boundary conditions.