# fracture connectivity command

Syntax

- fracture connectivity keyword <range>
Primary keywords:

aperture cubic distance extra-index starting-fracture starting-geometry intersection-set

Calculate fracture connectivity with a specified structure. The initial structure can either be a fracture or a geometry set. By default, integer connectivity levels are computed for each fracture (i.e., a connectivity level of n means that the fracture is connected to the structure through n fracture intersections), and extras are assigned based on the distance. This behavior can be modified with the aperture, cubic and distance keywords. If either no intersection set is specified or the specified intersection set does not exist, a new intersection set is created and all intersections between fractures are delineated; the resulting intersection set is used as the basis for the connectivity calculation.

- aperture
Connectivity is assigned to the extra variable in a index specified with the extra-index keyword. Connectivity is the distance (as defined in the description of the distance keyword) divided by the fracture aperture.

- cubic
Connectivity is assigned to the extra variable in a index specified with the extra-index keyword. Connectivity is the distance (as defined in the description of the distance keyword) divided by the cube of the fracture aperture (i.e., similar to the transmissivity).

- distance
Connectivity is assigned to the extra variable in an index specified with the extra-index keyword. Connectivity is given as the physical distance from the structure to the fracture, calculated as the path through the centers of intersections.

- extra-index i
The connectivity is calculated, and this keyword specifies the extra index for assignment. The extra index 1 is used if this keyword is not specified.

- starting-fracture i
The starting structure is set to the fracture with ID i. This keyword cannot be specified with the starting-geometry keyword.

- starting-geometry s
The starting structure is set to the geometry set with name s. This keyword cannot be specified with the starting-fracture keyword.

- intersection-set s
Specify the intersection set name used for connectivity calculation. If no intersection set is specified a new intersection set is created with name intersectionsXX, where XX is the next available intersection set ID.

Usage Example

The following example illustrates how the `fracture connectivity`

command can compute the connectivity level from a
borehole, and the connectivity distance from a fracture. It first calculates the connectivity level from the borehole
previously defined, and saves the level in extra 1. Fractures with a connectivity level of 0 are directly connected to
the borehole, fractures with a level of 1 are connected to the level 0 fractures, etc. Fractures with a negative
connectivity level (-1) are disconnected. Then, it computes the distance of all fractures to the fracture with ID 1 and
saves it in extra 2. This distance can be used later for analysis purposes or to simplify the DFN
(e.g., by removing fractures that are too far from a given structure).

```
model new
model random 10000
model domain extent -5 5 -5 5 -5 5
;Create a borehole geometry
geometry set 'borehole'
geometry edge create by-position (-5,0,0) (5,0,0)
;Generate fractures using the default template
fracture generate percolation 5
;Calculate connectivity starting with the borehole
fracture connectivity starting-geometry 'borehole' extra-index 1
;Calculate connectivity starting with fracture 1
fracture connectivity starting-fracture 1 extra-index 2 distance
return
```

See Also: `fracture cluster`

| `fracture intersections compute`

Was this helpful? ... | PFC 6.0 © 2019, Itasca | Updated: Sep 25, 2020 |