Cubit
15.3 User
Documentation
Cubit
15.3 User
Documentation
The metrics used for triangular elements in CUBIT are summarized in the following table:
|
Function Name
|
Dimension
|
Full Range
|
Acceptable Range
|
Reference
|
|
Element Area
|
L^2
|
0 to inf
|
None
|
1
|
| Maximum Angle |
degrees
|
60 to 180
|
60 to 90
|
1
|
| Minimum Angle |
degrees
|
0 to 60
|
30 to 60
|
1
|
| Condition No |
L^0
|
1 to inf
|
1 to 1.3
|
2
|
| Scaled Jacobian |
L^0
|
-1 to 1
|
0.2 to 1
|
2
|
| Relative Size |
L^0
|
0 to 1
|
0.25 to 1
|
3
|
| Shape |
L^0
|
0 to 1
|
0.25 to 1
|
3
|
| Shape and Size |
L^0
|
0 to 1
|
0.25 to 1
|
3
|
| Distortion |
L^2
|
-1 to 1
|
0.6 to 1
|
4
|
Element Area: (1/2) * Jacobian at corner node
Maximum Angle: Maximum included angle in triangle
Minimum Angle: Minimum included angle in triangle
Condition No. Condition number of the Jacobian matrix
Scaled Jacobian: Minimum Jacobian divided by the lengths of 2 edge vectors
Relative Size: Min( J, 1/J ), where J is determinant of weighted Jacobian matrix
Shape: 2/Condition number of weighted Jacobian matrix
Shape & Size: Product of Shape and Relative Size
Distortion: {min(|J|)/actual area}*parent area, parent area = 1/2 for triangular element
Relative Size, Shape, and Shape & Size are algebraic metrics, which have well behaved properties. Cubit encourages the use of these metrics over other metrics. These metrics are referenced to an ideal element which, in the case of triangular elements, is an equilateral triangle. Thus deviations from an equilateral triangle are measured in various ways by the algebraic metrics.
Relative size measures the size of the element vs. the size of reference element. If the element is twice or one-half the size of the reference element, the relative size is one-half. By default, the size of the reference element is the average size of all the elements that the quality command is currently evaluating.
The shape and size metric measures how both the shape and relative size of the element deviate from that of the reference element.