NESC9578 FACET.

1. NAME OR DESIGNATION OF PROGRAM:  FACET.

3. DESCRIPTION OF PROGRAM OR FUNCTION

FACET calculates the radiation  geometric view factor (alternatively called shape factor, angle factor, or configuration factor) between surfaces for axisymmetric,  two-dimensional planar and three-dimensional geometries with interposed third surface obstructions. FACET was developed to calculate view factors as input data to finite element heat transfer analysis codes.

4. METHOD OF SOLUTION

Three algorithms are incorporated to integrate  the view factor equation for three dimensional geometries. The algorithm used for any two surfaces depends on their geometric relationship and whether third surface obstructions exist. The three algorithms are the area integration (AI) method, the line integration method (LI), and the Mitalas and Stephenson (MS) method. The LI method is used to calculate the view factor between two disjoint surfaces. If the two surfaces have an adjoint edge, the MS  method is used. The AI method is used if there is self or third surface shadowing. In two-dimensional planar geometries, the view factor between two surfaces is calculated using Hottel's cross string method. For axisymmetric geometries in the absence of shadowing, the view factor between two surfaces is calculated by view factor algebra using the view factors between parallel coaxial  discs. In the presence of self or third surface shadowing, the geometry is represented in three dimensions before calculating the view factors.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM:

6. TYPICAL RUNNING TIME:

The test case supplied with this package was executed at NEA-DB on a VAX 8810 computer in 0.60 seconds of CPU time.

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS

The FACET plot file containing the  geometry data can be viewed using TAURUS (NESC 9908). CNVUFAC (NESC  9911) can be used to calculate the geometric black body radiation node to node view factors. GRAY (NESC 9911) uses the black body view factors calculated by CNVUFAC to determine gray body exchange factors required by thermal analyzer codes. MONTE uses a Monte Carlo method to calculate exchange factors for specular emitting and reflecting surfaces for two-dimensional planar geometries.

10. REFERENCES

- Arthur B. Shapiro
FACET - A Radiation View Factor Computer Code for Axisymmetric, 2D    Planar, and 3D Geometries with Shadowing,
  UCID-19887, August 1983.
- FACET, NESC No. 9578, FACET Tape Description and Implementation
  Information,
  National Energy Software Center Note 87-102, September 25, 1987.
- Robert L. Wong
  User's Manual for CNVUFAC, the General Dynamics Heat-Transfer
  Radiation View Factor Program,
  UCID-17275, June 25, 1976.
- Robert L. Wong
  GRAY: A Program to Calculate Gray-Body Radiation Heat Transfer
  View Factors from Black Body View Factors,
  UCID-17277, June 14, 1976.

- Arthur B. Shapiro :
  FACET : A Radiation View Factor Computer Code for Axisymmetric, 2D
  Planar, and 3D Geometries with Shadowing
  UCID-19887 (August 1983)
- P. Johnson :
  FACET Tape Description and Implementation Information
  NESC Note 87-102 (September 25, 1987)

11. MACHINE REQUIREMENTS:

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:

VAX/VMS V5.0-1 (VAX 8810).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHORS

          A.B. Shapiro
          Mechanical Engineering Department
          Lawrence Livermore National Laboratory

File name	File description	Records
NESC9578_01.001	Information file	59
NESC9578_01.002	Fortran source	3709
NESC9578_01.003	Sample input data	7
NESC9578_01.004	Sample output file	91