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The S2S radiation model is computationally very expensive when there are a large num-ber of
radiating surfaces. To reduce the memory requirement for the calculation, the number of radiating
surfaces is reduced by creating surface clusters. The surface cluster information (coordinates and
connectivity of the nodes, surface cluster IDs) is used by ANSYS FLUENT to compute the view factors
for the surface clusters.

(a) Computing View Factors

ANSYS FLUENT can compute the view factors for your problem in the current session and save them to
a file for use in the current session and future sessions. Alternatively, you can save the surface cluster
information and view factor parameters to a file, calculate the view factors outside ANSYS FLUENT,
and then read the view factors into ANSYS FLUENT. These methods for computing view factors are
described below.

(b) Computing View Factors Inside ANSYS FLUENT
To compute view factors in your current ANSYS FLUENT session, you must first set the parameters for
the view factor calculation in the View Factor and Cluster Parameters dialog box (see below for
details). When you have set the view factor and surface cluster parameters, click Compute/Write...
under Methods in the Radiation Model dialog box. A Select File dialog box will open, prompting you for
the name of the file in which ANSYS FLUENT should save the surface cluster information and the view
factors. After you have specified the file name, ANSYS FLUENT will write the surface cluster
information to the file. ANSYS FLUENT will use the surface cluster information to compute the view
factors, save the view factors to the same file, and then automatically read the view factors. The ANSYS
FLUENT console will report the status of the view factor calculation. For example:
Completed 25% calculation of view factors

Completed 50% calculation of view factors
Completed 75% calculation of view factors
Completed 100% calculation of view factors

4.4.3 Setting Up the Solar Load Model
The solar load model is enabled in the Radiation Model dialog box.

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