VFCO
VFCO, Action,
ENCL, LEVEL
Controls the use and level of view factor condensation for symmetric
radiation.
ActionAction to be performed:
DEFINE
—
Defines the level of view factor condensation (default).
CLEAR
—
Resets the level of view factor condensation to 0 for all enclosures. All subsequent arguments are ignored.
STATUS
—
Outputs the
LEVELof view factor condensation for each enclosure in the model.ENCLPreviously defined enclosure number for the view factor adjustment.
LEVELKey that controls the level of condensation used in calculating the view factor matrix for models with symmetry. Efficiency gains increase with increasing values of
LEVEL.0
—
View factor condensation is turned off (default). The view factor matrix is calculated for all facets, as described in View Factor Matrix: General in the Theory Reference.
1
—
View factor condensation is turned on. With condensation on, view factors for dependent facets are not calculated, which reduces solution time for models with symmetry. The view factor matrix is calculated only for independent facets as described in View Factor Matrix for a Model with Symmetry in the Theory Reference. This option achieves better efficiency than
LEVEL= 0. Element NMISC data is written to the results file for both independent and dependent facets.*GET,,RAD,,NETHF, which also uses element fluxes, is based on independent and dependent facets.2
—
This option achieves even more efficiency gains than
LEVEL= 1, but it requires more memory and loses some information. Note that whenLEVEL= 2 is used, dependent facets are unselected, and no element NMISC data is written to the results file for dependent facets. The same is true for *GET,,RAD,,NETHF, which also uses element fluxes and is based on independent facets only.
Notes
If view factor condensation is turned on
(VFCO,,ENCL,1 or
VFCO,,ENCL,2):
The dependent facets do not participate in the solution, and only the independent view factors are calculated as described in View Factor Matrix for a Model with Symmetry in the Theory Reference.
The problem is reduced to solving only for the independent radiosity flux as described in Radiosity Equations Simplified for Models with Symmetry in the Theory Reference.
The VFSM command operates on the condensed view factor matrix.
VFCO must be issued before the view factors are computed by issuing either VFOPT,NEW or SOLVE.