Post-Processing Surface Radiation Exchanges

Simcenter STAR-CCM+ allows you to analyze radiative quantities on transmissive and reflective boundaries.

For boundaries with transmissivity = 1 or specular reflectivity = 1, you can post-process the following quantities:

Irradiation - the radiative heat flux incident on a surface
Mean Radiant Temperature (MRT)
Direct solar irradiation - the direct solar flux on the boundary.

For example, consider a thermal comfort case where a car driver experiences solar irradiation:

You can view the solar irradiation falling on the driver.
You can view the direct solar irradiation on the windows (transmissivity = 1).

Boundaries with specular reflectivity + transmissivity = 1 are called "fully specular boundaries." On fully specular boundaries, the total irradiation accounts for irradiation from other boundaries, solar radiation (direct and diffuse), and radiation from the environment, if any.

Fully specular boundaries do not participate in the solution of surface radiation exchange and energy equations; zero net radiative flux exists across them.

If you use the Surface-to-Surface model, you can generate a summary of detailed radiation exchange among boundaries, by right-clicking the S2S solver node and selecting Display Detailed Radiation Exchange. The summary is printed in the output window.

Example output:

Incoming Radiation is the radiation coming from a given source boundary (listed under Boundary 2) to a given target boundary (listed under Boundary 1).
Outgoing Emission is the emission (thermal and user-specified combined) released by a given source boundary (listed under Boundary 1) going towards a given target boundary (listed under Boundary 2).
Radiative Flux is the difference between the absorbed portion of the incoming radiation (absorptivity $\times$ Incoming Radiation) and the outgoing emission for a given pair of target and source boundaries listed under Boundary 1 and Boundary 2.

The calculation for this summary does not include boundaries with symmetric or periodic conditions, or fully specular boundaries. Symmetry and periodic boundaries contribute to the radiation heat transfer only by reflecting or periodically transforming the radiative energy in the correct direction. Both types of boundaries are compatible with post-processing of S2S radiation and refraction.

Note	If view factors or patches have not been calculated or the solution does not exist, detailed exchange post-processing is automatically disabled in GUI.