The Sun Properties feature defines the Sun position and the solar flux.
Select any of the predefined option for the Sun direction (
Winter solstice,
Summer solstice,
Spring equinox, or
Fall equinox) to define the Sun vector and solar flux. In this case the
Sun vector in ECS field is not editable and show the vector definition for the selected value.
When the Solar flux is set to
Automatic a Plank’s distribution for a blackbody at
Ts = 5780 K is used for the radiation in case of multiple spectral bands. The solar flux intensity (SI unit W/m
2) is defined according to
Table 6-6.
The Solar flux can also be set to
User defined and
User defined per band in case of multiple spectral bands. In case of gray surface model, only
User defined is available.
When the Sun direction is set to
User defined, the S
un vector in ECS field is editable. The
Solar flux can be defined similarly as above except that the
Automatic option is not available.
When the Solar flux is set to
User defined for each band, enter a value for the
Solar flux,
q0s,i (SI unit W/m
2, default value 0W/m
2) for each spectral band. Within a spectral band, each value is assumed to be independent of wavelength.
When Solar flux is set to
User defined, define
q0s,λ (SI unit W/m
3, default value 0W/m
3). The wavelength may be accessed through the
otl.lambda variable. This distribution is integrated on each spectral band to obtain the source heat flux
q0s,i for each spectral band.
Any Clear sky noon beam normal irradiance defined from an
Ambient properties node can also be selected to define
q0s. In this case spectral the bands the solar flux distribution per band is defined following Plank's distribution for a blackbody at
Ts.