`elem`¶

Element connectivity data. These data are usually created by a mesh generation program, then cut and copied into the input file or a separate geometry data input file.

Note

elem is required if macro fdm is not used.

Group 1 - NS, NEI
Group 2 - MB, NELM (1), NELM (2), …, NELM (NS)

If \(NS < 0\) then \(ABS(NS)\) is interpreted as the number of nodes per element. \(NS < 0\) signals the code to make rectangles (or bricks in three dimensions) a sum of triangles (or tetrahedrals). This provides more stability in nonlinear problems with a distorted mesh. See Elements available with FEHM in 2-D and 3-D problems showing nodal numbering convention. shows available element types and the nodal numbering convention. To end the control section a blank line is entered.

Input Variable	Format	Description
`NS`	integer	Number of nodes per element.
`NEI`	integer	Number of elements
`MB`	integer	Element number. `If MB < 0` then the difference between the absolute value of MB and the previous absolute value of MB is used to generate intermediate values by interpolation in the code.
`NELM (1)`	integer	First node of element MB
`NELM (2)`	integer	Second node of element MB
…
`NELM (NS)`	integer	Last node of element MB

The following is an example of elem. In this example there are 4 nodes per element, i.e., the elements are 2-dimensional quadrilaterals. There are a total of 117 elements in the model, element number 1 is defined by nodes 15, 16, 2, and 1, element number 2 is defined by nodes 16, 17, 3 and2, and so on.

elem
4	117
1	15	16	2	1
2	16	17	3	2
.	.	.	.	.
.	.	.	.	.
.	.	.	.	.
10	24	25	11	10
11	25	26	12	11
12	26	27	13	12
.	.	.	.	.
.	.	.	.	.
.	.	.	.	.
116	138	139	125	124
117	139	140	126	125

elem¶

`elem`¶