*GAP FLOW

Define constitutive parameters for tangential flow in pore pressure cohesive elements and enriched elements.

This option is used to define tangential flow constitutive parameters for pore pressure cohesive elements and enriched elements. It is usually used in a model with hydraulically driven fracture.

This page discusses:

Optional parameters
Data lines to define the pore fluid viscosity $(μ)$ (TYPE=NEWTONIAN)
Data lines to define the consistency, K, and exponent, $α$ (TYPE=POWER LAW)
Data lines to define the consistency, K, and the yield stress, $τ_{0}$ (TYPE=BINGHAM PLASTIC)
Data lines to define the consistency, K; exponent, $α$ ; and yield stress, $τ_{0}$ (TYPE=HERSCHEL-BULKLEY)
Data lines to define the pore fluid viscosity $(μ)$ (TYPE=NEWTONIAN with the SLURRY parameter)
Data lines to define the consistency, K, and exponent, $α$ (TYPE=POWER LAW with the SLURRY parameter)
Data lines to define the consistency, K, and the yield stress, $τ_{0}$ (TYPE=BINGHAM PLASTIC with the SLURRY parameter)
Data lines to define the consistency, K; exponent, $α$ ; and yield stress, $τ_{0}$ (TYPE=HERSCHEL-BULKLEY with the SLURRY parameter)

See Also

In Other Guides

Defining the Constitutive Response of Fluid within the Cohesive Element Gap

Defining the Constitutive Response of Fluid Flow within the Cracked Element Surfaces

Products Abaqus/Standard Abaqus/CAE

Type Model data

LevelModel

Abaqus/CAE Property module

Optional parameters

DEPENDENCIES

Set this parameter equal to the number of field variables included in the definition of the constitutive parameters, in addition to temperature. If this parameter is omitted, it is assumed that the constitutive parameters are constant or depend only on temperature. See Material Data Definition for more information.

FLUID ID

Set this parameter equal to the fluid identifier when multi-fluid tangential flow is specified.

KMAX

Set this parameter equal to the maximum permeability value that should be used. This parameter is meaningful only when TYPE=NEWTONIAN. If this parameter is omitted, Abaqus assumes that the permeability is not bounded.

PTAU

Set this parameter equal to a scalar value $P_{τ}$ used to compute the still fluid viscosity before yielding as $μ = P_{τ} \times K$ . The default value of $P_{τ}$ is 10⁷.

This parameter can be used only with TYPE=BINGHAM PLASTIC and TYPE=HERSCHEL-BULKLEY.

SETTLING

This parameter specifies the formulation used to define the proppant settling behavior during slurry transport. It can be used only in conjunction with the SLURRY parameter.

If this parameter is omitted or used without a value (default), a built-in settling mechanism is applied.

Set SETTLING=NONE to neglect settling effects.

Set SETTLING=USER to specify a user-defined settling velocity field through user subroutine USETTLING.

SLURRY

Include this parameter to define tangential flow constitutive properties that depend on slurry concentration.

TYPE

Set TYPE=NEWTONIAN (default) to define the viscosity for a Newtonian fluid.

Set TYPE=POWER LAW to define the consistency and exponent for a power law fluid.

Set TYPE=BINGHAM PLASTIC to define the consistency and the yield stress for a Bingham plastic fluid.

Set TYPE=HERSCHEL-BULKLEY to define the consistency, exponent, and yield stress for a Herschel-Bulkley fluid.

Data lines to define the pore fluid viscosity $(μ)$ (TYPE=NEWTONIAN)

First line

$μ$ .
Temperature, $θ$ .
First field variable.
Second field variable.
Etc., up to six field variables.

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

Seventh field variable.
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 consistency, K, and exponent, $α$ (TYPE=POWER LAW)

First line

K.
$α$ .
Temperature, $θ$ .
First field variable.
Second field variable.
Etc., up to five field variables.

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

Sixth field variable.
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 consistency, K, and the yield stress, $τ_{0}$ (TYPE=BINGHAM PLASTIC)

First line

K.
$τ_{0}$ .
Temperature, $θ$ .
First field variable.
Second field variable.
Etc., up to five field variables.

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

Sixth field variable.
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 consistency, K; exponent, $α$ ; and yield stress, $τ_{0}$ (TYPE=HERSCHEL-BULKLEY)

First line

K.
$α$ .
$τ_{0}$ .
Temperature, $θ$ .
First field variable.
Second field variable.
Etc., up to four field variables.

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

Fifth field variable.
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 pore fluid viscosity $(μ)$ (TYPE=NEWTONIAN with the SLURRY parameter)

First line

$μ$ .
Slurry concentration, $C_{v}$ .
Temperature, $θ$ .
First field variable.
Second field variable.
Etc., up to five field variables.

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

Sixth field variable.
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 consistency, K, and exponent, $α$ (TYPE=POWER LAW with the SLURRY parameter)

First line

K.
$α$ .
Slurry concentration, $C_{v}$ .
Temperature, $θ$ .
First field variable.
Second field variable.
Etc., up to four field variables.

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

Fifth field variable.
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 consistency, K, and the yield stress, $τ_{0}$ (TYPE=BINGHAM PLASTIC with the SLURRY parameter)

First line

K.
$τ_{0}$ .
Slurry concentration, $C_{v}$ .
Temperature, $θ$ .
First field variable.
Second field variable.
Etc., up to four field variables.

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

Fifth field variable.
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 consistency, K; exponent, $α$ ; and yield stress, $τ_{0}$ (TYPE=HERSCHEL-BULKLEY with the SLURRY parameter)

First line

K.
$α$ .
$τ_{0}$ .
Slurry concentration, $C_{v}$ .
Temperature, $θ$ .
First field variable.
Second field variable.
Third field variable.

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

Fourth field variable.
Etc., up to eight field variables per line.

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