MESHING DIVISION Control Part_name Parameter

                            

The MESHING DIVISION command is used to control the number of elements that will be created when a mesh is generated.

Control Part_name Parameter Comments

LINE ALL n Defines the number of elements by

Line_name n division of lines. (See note 1).

Set_name n If a line_name is specified the word LINE is optional.

SURFACE ALL n1 n2 Defines the number of elements by

Surface_name n1 n2 division of surfaces. (See note 2).

Set_name n1 n2 If a surface_name is specified the word SURFACE is optional.

BODY ALL n1 n2 n3 Defines the number of elements by

Body_name n1 n2 n3 division of bodies. (See note 3).

Set_name n1 n2 n3 If a body_name is specified the word BODY is optional.

FACTOR ALL Factor Multiplies the number of divisions by

Line_name Factor the factor (See note 4).

Surface_name Factor

Body_name Factor

Set_name Factor

ELSIZE ALL Length Set the number of divisions by the

Line_name Length length of an element edge.

Surface_name Length (See note 5).

Body_name Length

Set_name Length

AUTOMATIC Adjust the number of divisions automatically. (See note 6).

RELATIVE ALL n Adds the input value to the number

Line_name n of divisions (may be negative).

Surface_name n

Body_name n

Set_name n

DEFAULT -- n Sets the default number of divisions.

/PICK n1 [n2] [n3] Allows the part to be picked

Return Level: MESHING DIVISION Control except for part name ALL and controls AUTOMATIC and DEFAULT which return to the top level.

Notes:

1.

Division of lines
If the nodes are to be evenly spaced along the line, `n' is the number of divisions on a line . In this case `n' must be less than 100. If you wish to control the spacing of the nodes `n' is calculated as follows:-

`n' = Sign(IQ*100+IE) (an integer), where:

IQ = quotient of the lengths of the largest and the smallest element edge on the line (integer $<10$ ). This is called the grading value.

Sign + : elements are smaller at start point of line .

Sign - : elements are smaller at end point of line .

IE = number of elements with no midside nodes that can be generated along the line. The number of elements with midside nodes that can be generated is = IE/2 (IE must be even for these elements). If `divn' is not specified the default value is used. IE must be $<100$.

 

Figure 2.87: Spacing nodes on a line using a grading value

2.

Divisions of surfaces
`n1' = division along the first and third sides of the surface. IQ must be = 0. (see note 1. above).

`n2' = division along the second and fourth sides of the surface. IQ must be = 0.

 

Figure 2.88: Examples of grading control on surfaces

3.

Divisions of bodies
`n1' = division along the first and third sides of the bottom surface. IQ must be = 0. (see note 1. above)

`n2' = division along the second and fourth sides of the bottom surface. IQ must be = 0.

`n3' = division along the sides from bottom to top surface. IQ must be = 0.

4.

Multiplying divisions by a factor
`Factor' is a real number which will multiply the divisions on all lines in 'part'. The new division is rounded off to the nearest integer value. The grading value is kept unchanged.

5.

Setting divisions by element edge length
`Length' is the requested element side length. It is used to calculate a `divn'-value for all lines in `part'. The new division is rounded off to the nearest integer value. The grading value is kept unchanged.

6.

Setting divisions automatically
All surfaces and bodies in the structure will be checked to comply with the rules of division (see command MESHING TYPES). If e.g. a surface is found that cannot be meshed, FEMGEN tries to change the division on one line in the surface (a warning is written). If it fails to make a surface meshable, an error message is given.

Examples:

1.

MESHING DIVISION LINE L3 4

Define four equal divisions on line L3.

2.

MESHING DIVISION LINE L1 -406

Define six unequal divisions on line L1. The divisions are biased towards the start point of the line. The ratio of largest to smallest division is 4.

3.

MESHING DIVISION SURFACE S6 3 4

Define three equal divisions on sides 1 and 3, and four equal divisions on sides 2 and 4, for surface S6.

4.

MESHING DIVISION SURFACE SET1 3 4

Define all divisions on surfaces within set SET1 as per the previous example.

5.

MESHING DIVISION BODY B1 2 2 4

Define divisions on body B1. Two equal divisions on sides 1 and 3 of the bottom surface, two equal divisions on sides 2 and 4 of the bottom surface, and four equal divisions on all sides connecting the top and bottom faces.

6.

MESHING DIVISION BODY ALL 1 2 3

Define divisions for all bodies in the model. One division on sides 1 and 3 of the bottom surface, two equal divisions on sides 2 and 4 of the bottom surface, and three equal divisions on all sides connecting the top and bottom faces.

See also the following commands

'GEOMETRY LINE'
'LABEL GEOMETRY DIVISIONS'