*PERMEABILITY

Define permeability for pore fluid flow.

This option is used to define permeability for pore fluid flow in problems involving seepage and porous media.

 

See Also
Permeability

Defining permeability in Abaqus/Standard analyses

Optional parameters

DEPENDENCIES

Set this parameter equal to the number of field variable dependencies included in the definition of the permeability. If this parameter is omitted, it is assumed that the permeability is independent of field variables.

This parameter can be used only in conjunction with TYPE=ISOTROPIC, ORTHOTROPIC, or ANISOTROPIC.

STABILIZE

This parameter applies only to first-order solid continuum elements with full integration.

Include this parameter to add a stabilization term to the element operator and the right-hand-side term by projecting the pressure into the strain space to eliminate the pressure oscillations for materials with very low permeability.

Set this parameter equal to a value by which Abaqus/Standard multiplies the shear modulus and the time increment to form the stabilization term in the element operator.

If this parameter is included without a value specified, the default stabilization coefficient value is 100.

TYPE

Set TYPE=ISOTROPIC (default) to define fully saturated isotropic permeability. Set TYPE=ORTHOTROPIC to define fully saturated orthotropic permeability. Set TYPE=ANISOTROPIC to define fully saturated anisotropic permeability.

Set TYPE=SATURATION to define ks⁢(s); this must be a repeated use of the option for the same material and must follow the definition of fully saturated permeability. The definition must give ks for 0.0<s≤1.0, with ks=1.0 at s=1.0.

Set TYPE=VELOCITY to define β⁢(e); this must be a repeated use of the option for the same material and must follow the definition of fully saturated permeability.

Required parameter when fully saturated material properties are defined

SPECIFIC

Set this parameter equal to the specific weight of the wetting liquid, γw (units of FL−3). The actual specific weight must be given as a nonzero positive value, and the GRAV distributed load type must be used to apply the gravitational loading if a total pressure solution is required (see Coupled Pore Fluid Diffusion and Stress Analysis for a discussion of total and excess pressure solutions).

Data lines to define fully saturated isotropic permeability (TYPE=ISOTROPIC)

First line

  1. k. (Units of LT−1.)

  2. Void ratio, e.

  3. Temperature, θ.

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the variation.

Data lines to define fully saturated orthotropic permeability (TYPE=ORTHOTROPIC)

First line

  1. k11. (Units of LT−1.)

  2. k22.

  3. k33.

  4. Void ratio, e.

  5. Temperature, θ.

  6. First field variable.

  7. Second field variable.

  8. Third field variable.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than three)

  1. Fourth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the variation.

Data lines to define fully saturated anisotropic permeability (TYPE=ANISOTROPIC)

First line

  1. k11. (Units of LT−1.)

  2. k12.

  3. k22.

  4. k13.

  5. k23.

  6. k33.

  7. Void ratio, e.

  8. Temperature, θ.

Subsequent lines (only needed if the DEPENDENCIES parameter is specified)

  1. First field variable.

  2. Second field variable.

  3. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the variation.

Data lines to define the dependence of permeability on saturation of the wetting liquid, ks(s) (TYPE=SATURATION)

First line

  1. ks. (Dimensionless.)

  2. Saturation, s. (Dimensionless.)

Repeat this data line as often as necessary to define the variation. The table must provide ks=1.0 at s=1.0.

Data lines to define the velocity coefficient (TYPE=VELOCITY)

First line

  1. β. (Units of TL−1.) Only β>0.0 is allowed.

  2. Void ratio, e.

Repeat this data line as often as necessary to define the variation.