Slip Dependent Permeability Model

Overview

The slip dependent permeability model defines the relationship between the relative shear displacement and fracture permeability. In this model, fractrues/faults are represented as slip interfaces.

$k = k_{i} \left[ (M_{mult} - 1) \text{tanh} \left( 3 \frac{ U_{s} }{ U_{s_{threshold}} } \right) + 1 \right]$

where $k_{i}$ is the initial fracture permeability; $M_{mult}$ is the maximum permeability multiplier; $U_{s}$ is the relative shear displacement; $U_{s_{threshold}}$ is the slip threshold.

Parameters

The Slip Dependent Permeability model can be called in the <Constitutive> block of the input XML file. This permeability model must be assigned a unique name via the name attribute. This name is used to assign the model to regions of the physical domain via a permeabilityModelName attribute in the <CompressibleSolidSlipDependentPermeability> block.

The following attributes are supported:

XML Element: SlipDependentPermeability

Name	Type	Default	Description
initialPermeability	R1Tensor	required	initial permeability of the fracture.
maxPermMultiplier	real64	required	Maximum permeability multiplier.
name	groupName	required	A name is required for any non-unique nodes
shearDispThreshold	real64	required	Threshold of shear displacement.

Example

<Constitutive>
   ...
   <SlipDependentPermeability
     name="fracturePerm"
     shearDispThreshold="0.005"
     maxPermMultiplier="1000.0"
     initialPermeability="{1e-15, 1e-15, 1e-15}"/>
   ...
</Constitutive>