# fracture template modify-default command

Syntax

fracture template modify-default keyword

Primary keywords:

Modify the default fracture generation template. A fracture generation template is a set of statistical parameters used to generate fractures with the fracture generate command. If no fracture generation template is specified, the default template is used. Upon a model new, the default fracture generation template is given the following properties: 1) uniform fracture positions; 2) uniform fracture orientations (dip between 0 and 180 degrees in 2D; dip between 0 and 90 degrees, dip direction between 0 and 360 degrees in 3D); 3) fracture sizes obeying a negative power-law distribution with exponent 4; and 4) minimum fracture size is size 1.0 and maximum fracture size is ∞. The default fracture generation template is saved with the model state and a DFN cannot be linked to the default template. The following keywords may be applied:

dip-direction-limits fmin fmax (3D only)

Specify that the fracture dip directions must fall in the range [fmin, fmax] degrees. By default, fmin = 0 and fmax = 360.

dip-limits fmin fmax

Specify that the fracture dips must fall in the range [fmin, fmax] degrees. By default, {fmin = 0 and fmax = 180, in 2D; fmin = 0 and fmax =90, in 3D}.

orientation s a1...an

Define the generation rule for fracture orientations with the parameters $$a_{1}...a_{n}$$. The following options for s are supported:

• bootstrapped: The dip {and dip direction, in 3D} are bootstrapped from a file. One parameter must be given: the file name holding the discrete distribution of values. This file obeys the bootstrapped distribution file format given in DFN-Related File Formats.
• dips (3D only): The dip and dip direction are bootstrapped from a DIPS file. One parameter must be given: the file name holding the discrete distribution of values. This file obeys the DIPS file format given in DFN-Related File Formats.
• fish: The fish keyword is used to get values from a user-defined FISH function. The function name is given using $$a_{1}$$, and the function arguments (any number) are given after the function name. The function must return a {float, in 2D; 2 dimensional vector, in 3D}.
• fisher (3D only): The dip and dip direction are drawn from a Fisher distribution. Three additional parameters are required: dip, dip direction and $$\kappa$$.
• gauss: The dip {and dip direction, in 3D} are drawn from Gaussian distributions. In 2D, two additional parameters are required, specifying the mean and standard deviation of the dip distribution. In 3D, four additional parameters are required: mean and standard deviation for the dip distribution, followed by mean and standard deviation for the dip-direction distribution.
• uniform: The dip {and dip direction, in 3D} are drawn from a uniform distribution. No additional parameters can be given.

Note

In 2D, dip is the clockwise angle measured from the positive $$x$$-axis in degrees. In 3D, dip is the angle from the dip direction projected on the $$xy$$-plane to the fracture surface measured in the negative $$z$$-direction. Dip direction in 3D is measured in a clockwise fashion from the positive $$y$$-axis.

position s a1...an

Define the generation rule for fracture position with parameters . The supported options for s are uniform, gauss, bootstrapped and fish. The meaning of these keywords is the same as for the orientation keyword except that the position is a {2D vector in 2D; 3D vector in 3D}. Consequently, if bootstrapped is specified, the file must contain the required number of values, and if fish is specified, the FISH function must return a vector of correct dimension. Additionally, the mean and standard deviations must be vectors if the gauss keyword is specified.

size s a1...an

Define the distribution of fracture sizes. The fracture size is defined as the {fracture length, in 2D; disk diameter, in 3D}. The supported options for s are uniform, gauss, power-law, bootstrapped and fish. The power-law specifier defines a negative power-law distribution which requires one parameter that is the exponent of the distribution with > 0. The remaining s options are as specified in the orientation description, except that the return value is a floating point value. Thus, only two arguments follow the gauss specifier: the bootstrapped file must follow a one-dimensional format; and the fish function must return a single value.

size-limits fmin fmax

Fracture size limits must fall within the range [fmin, fmax]. By default, fmin = 1.0 and fmax = +∞. Fracture size is defined as the {length, in 2D; diameter, in 3D}.