RADOPT
RADOPT, --,
FLUXTOL, SOLVER,
MAXITER, TOLER,
OVERRLEX, --,
--, --, --,
MAXFLUXITER , CONSERVATION
Specifies Radiosity Solver options.
--Unused field.
-
FLUXTOL Convergence tolerance for radiation flux. Defaults to 0.0001. This value is a relative tolerance.
-
SOLVER Choice of solver for radiosity calculation:
0
—
Gauss-Seidel iterative solver.
1
—
Direct solver.
2
—
Jacobi iterative solver (default).
-
MAXITER Maximum number of iterations for the iterative solvers (
SOLVER= 0 or 2). Defaults to 1000.-
TOLER Convergence tolerance for the iterative solvers (
SOLVER= 0 or 2). Defaults to 0.1.If
TOLER≥ 0, the value is interpreted as an absolute tolerance. IfTOLER< 0, it is interpreted as a relative tolerance.-
OVERRLEX Over-relaxation factor applied to the iterative solvers (
SOLVER= 0 or 2). Defaults to 0.1.-
--,--,--,-- Unused fields
-
MAXFLUXITER Maximum number of flux iterations to be performed according to the specified solver type:
0
—
If the FULL solver is specified (THOPT,FULL), convergence criteria are monitored and iterations are performed until convergence occurs. If the QUASI solver is specified (THOPT,QUASI), convergence criteria are ignored and one iteration is performed. This value is the default.
1, 2, 3, ...N
—
If the FULL solver is specified (THOPT,FULL), convergence criteria are monitored and iterations are performed until convergence occurs, or until the specified number of iterations has been completed, whichever comes first. If the QUASI solver is specified (THOPT,QUASI), convergence criteria are ignored and the specified number of iterations are completed.
To view
MAXFLUXITERusage illustrations, see Figure 3.5: FULL Solution Method When Radiosity Is Present and Figure 3.6: QUASI Solution Method When Radiosity Is Present.-
CONSERVATION Key to account for the midside node temperature of underlying solid elements for radiosity calculations. Under normal circumstations using lower order elements, this option does not need to be activated. However, when using higher elements, you can improve energy conservation by setting
CONSERVATION= 1.0
—
Not active (default). The midside node temperatures are not accounted for in the radiosity calculations.
1
—
Active. The midside node temperatures are accounted for in the radiosity calculations.
Command Default
The Jacobi iterative solver (SOLVER = 2) is the default; it is
only available for 3D models. If the analysis is 2D, the Gauss-Seidel iterative solver
(SOLVER = 0) is used instead.
Notes
The radiation heat flux is linearized, resulting in robust convergence.
The radiation flux norm for FLUXTOL is expressed as:
where i is the pass or iteration number and j is the surface facet for radiation.
For a sufficiently small absolute tolerance value, relative tolerance converges in fewer iterations than absolute tolerance. For a sufficiently large absolute tolerance value, relative tolerance may cause convergence difficulties.
For more information about FLUXTOL and
MAXFLUXITER usage, see Figure 3.5: FULL Solution Method When Radiosity Is Present and Figure 3.6: QUASI Solution Method When Radiosity Is Present in the Thermal Analysis Guide.
In Figure 3.5: FULL Solution Method When Radiosity Is Present and Figure 3.6: QUASI Solution Method When Radiosity Is Present (under Solving for Temperature and Radiosity in the Thermal Analysis Guide), refer to the KQQ = FQ equation system via the iterative method.
If TOLER ≥ 0, the iterative solver (SOLVER = 0 or 2) is converged for
maximum value over a different j as shown:
If TOLER < 0, the iterative solver (SOLVER = 0 or 2) is converged for
maximum value over a different j as shown:
where:
j = number of radiation facets |
k = number of iterations (k = 1 to
MAXITER) |
The Jacobi iterative solver (SOLVER = 2) is the only solver choice
that runs in a fully distributed parallel fashion. Therefore, it is typically the best choice for
optimal performance when running in distributed-memory parallel mode. Since the Jacobi iterative
solver is not available for 2D models, it is not possible to run 2D models in parallel
processes.