Parallel Plates Permeability Model

Overview

The parallel plates permeability model defines the relationship between the hydraulic fracture aperture and its corresponding permeability following the classic lubrication model (Witherspoon et al. ) . In this model, the two fracture walls are assumed to be smooth and parallel to each other and separated by a uniform aperture.

$k = \frac{a^3}{12}$

where $a$ denotes the hydraulic fracture aperture.

Remark: $k$ , dimensionally, is not a permeability (as it is expressed in $m^3$ ).

Parameters

The Parallel Plates 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 materialList attribute in the <ElementRegions> block.

The following attributes are supported:

Name	Type	Default	Description
name	groupName	required	A name is required for any non-unique nodes
transversalPermeability	real64	-1	Default value of the permeability normal to the surface. If not specified the permeability is updated using the cubic law.