View Factor Definition – Gaussian Integration Method
Description: Defines parameters to control view factor calculation for a specified cavity.
Format:
Example:
| Field | Definition | Type | Default | ||||||
|---|---|---|---|---|---|---|---|---|---|
| ICAVITY | Radiant cavity identification number on RADCAV entry. | Integer > 0 | |||||||
| MAXRU | Maximum number of recursions used in computing unobstructed view factors. See Remark 1. | Integer > 0 | 8 | ||||||
| MAXRO | Maximum number of recursions used in computing obstructed view factors. See Remark 1. | Integer > 0 | 8 | ||||||
| MINRO | Minimum number of recursions used in computing obstructed view factors. See Remark 2. | Integer ≥ 0 | 0 | ||||||
| ITOL | Integration convergence tolerance for both adaptive integration and view obstruction calculations. See Remark 3. | Real > 0.0 | 1.0E-5 | ||||||
| ZTOL | View factor calculation zero tolerance. Value below which computed view factors are considered to be zero. | Real ≥ 0.0 | 1.0E-10 | ||||||
| VFDOUT | View factor diagnostic output, one of the following character variables: YES or NO. When set to YES the following view factor calculation information is output to the Model Results Output File:
|
Character | NO |
Remarks:
- Limiting the maximum number of unobstructed recursions (MAXRU) or obstructed recursions (MAXRO) can reduce analysis time but may prevent reaching the specified convergence (ITOL). The default value provides a compromise between accuracy and analysis time.
- The default minimum number of obstructed recursions (MINRO) may miss an obstruction. Increasing the default value of 0 to 1 or 2 can prevent this but at the cost of increased analysis time. Typically increasing MINRO is not necessary except when very accurate view factors are desired.
- The value specified for ITOL is not an exact measure of the accuracy of the computed view factors, but smaller values will typically lead to more precise values. Values less than 1.0E-6 may not lead to improved accuracy.