OOF2: The Manual

`Rationalize (Rationalize)`
	6.5.2. Subclasses

Name

Rationalize (Rationalize) — Fix badly shaped elements in a Skeleton.

Synopsis

Rationalize(targets,criterion,method)

Details

Base class: SkeletonModifier
Parameters:

targets

Which elements to modify. Type: An object of the SkelModTargets class.

criterion

Acceptance criterion Type: An object of the SkelModCriterion class.

method

Methods for rationalization. Type: An object of the RationalizeMethod class.

Description

Rationalize fixes badly-shaped Elements in a Skeleton by either removing them or modifying them and their immediate neighbors. Besides being ugly, badly shaped elements can impair the convergence and accuracy of the finite element method.

OOF2 contains a number of different Rationalizer tools for rationalizing Skeletons. The method parameter determines whether the various tools will be applied automatically or whether only a specific set of tools should be used. Automatic rationalizing works better with a small set of target Elements. Specific rationalizing works well with any number of Elements.

The Rationalizer tools are applied sequentially. The general procedure for applying each tool is as follows:

Scan the current Skeleton for target elements according to the given targets parameter. The list of target Elements is shuffled to prevent artifacts from the original internal Element ordering.
Apply the Rationalizer to each Element in the target set. When using SpecificRationalization, only the Elements meeting the criteria specified in the Rationalizer's parameters are examined. When using AutomaticRationalization, all Elements are examined. The Rationalizer returns a list of possible new Element configurations.
Apply the given acceptance criterion to the new configurations, and choose the best one, if any.
Any new Elements created in step 3 are added to the target list, but only if the criterion is not of the Unconditional variety.^[32]
Return to step 2 until all Elements in the target list have been visited.

	Tip
	Remove Short Sides and Split Wide Quads inevitably create triangles and these triangles are not guaranteed to have good shapes. Thus, it's a good idea always to include Remove Bad Triangles in the set of tools to apply. It will always be applied after the other `Rationalizers`.

Figure 6.90 shows a Skeleton featuring six badly-shaped Elements -- two sharp triangles, a flat triangle, a quadrilateral with a wide interior angle, and two quadrilaterals sharing a short Segment.

Figure 6.90. Badly-shaped Elements

The Elements that will be rationalized are highlighted in red.

The rationalized Skeleton is presented in Figure 6.91. The short-sided quadrilaterals have been replaced with triangles, the sharp triangles have been eliminated, the wide quadrilateral has been split into two triangles, and the flat triangle has merged with a neighboring triangle and morphed into three triangles.

Figure 6.91. After Rationalization

The Elements affected by the rationalization are highlighted in red.

^[32] This is to avoid infinite loops.


`Range (RangeOutput)`		`Rebuild (RebuildMesh)`