Polymer Constitutive Equation

Polymer Constitutive Equation = {model_name}

Description / Usage

This required card is used to specify the polymer constitutive equation. A single input parameter must be defined, that being the {model_name}.

{model_name}

Name of the constitutive equation model, being one of the following values: NOPOLYMER, OLDROYDB, GIESEKUS, PTT, SARAMITO_OLDROYDB, SARAMITO_GIESEKUS, SARAMITO_PTT, WHITE-METZNER. Several of these polymer constitutive models require additional parameters for the polymer properties that are entered via additional cards, as described below. Please see the Example sectionand the tutorial referenced below.

Thus,

NOPOLYMER

For Newtonian and generalized Newtonian models. No floating point values are required.

OLDROYDB

For the Oldroyd-B constitutive model. This option requires four floating point values, which are described below.

GIESEKUS

For the Giesekus model. This option requires five floating point values, which are described below.

PTT

For the Phan-Thien Tanner model. This option requires six floating point values, which are described below.

SARAMITO_OLDROYDB

For the Oldroyd-B model used with the Saramito yield model. This option requires six floating point values, which are described below.

SARAMITO_GIESEKUS

For the Giesekus model used with the Saramito yield model. This option requires seven floating point values, which are described below.

SARAMITO_PTT

For the Giesekus model used with the Saramito yield model. This option requires eight floating point values, which are described below.

WHITE_METZNER

For the White-Metzner model. This option is not currently working.

Examples

The following is a sample card that sets the polymer constitutive equation to NOPOLYMER. This option does not require any additional cards since it indicates that there is no polymer constitutive equation present.

Polymer Constitutive Equation = NOPOLYMER

The following is a sample card that sets the polymer constitutive equation to OLDROYDB. This option requires four cards describing the polymer stress formulation, weight function, viscosity and time constant.

Polymer Constitutive Equation = OLDROYDB

Polymer Stress Formulation = EVSS_F

Polymer Weight Function = GALERKIN

Polymer Viscosity = CONSTANT 1.

Polymer Time Constant = CONSTANT 0.02

The following is a sample card that sets the polymer constitutive equation to GIESEKUS. This option requires five cards describing the polymer stress formulation, weight function, viscosity, time constant and mobility parameter.

Polymer Constitutive Equation = GIESEKUS

Polymer Stress Formulation = EVSS_F

Polymer Weight Function = GALERKIN

Polymer Viscosity = CONSTANT 1.

Polymer Time Constant = CONSTANT 0.2

Mobility Parameter = CONSTANT 0.1

The following is a sample card that sets the polymer constitutive equation to PHANTHIEN TANNER (or PTT). This option requires six additional cards that set the polymer stress formulation, weight function for the stress equation, viscosity, time constant and nonlinear PTT parameters.:

Polymer Consitutive Equation = PTT

Polymer Stress Formulation = EVSS_F

Polymer Weight Function = GALERKIN

Polymer Viscosity = CONSTANT 8000.

Polymer Time Constant = CONSTANT 0.01

PTT Xi parameter = CONSTANT 0.10

PTT Epsilon parameter = CONSTANT 0.05

An optional card PTT Form is available to choose between Linear and Exponential PTT forms. If not included EXPONENTIAL is the default.

Polymer Consitutive Equation = PTT
PTT Form = LINEAR

The following is a sample card that sets the polymer constitutive equation to SARAMITO_OLDROYDB. This option requires six cards describing the polymer stress formulation, weight function, viscosity, time constant, yield stress, and yield exponent.

Polymer Constitutive Equation = SARAMITO_OLDROYDB

Polymer Stress Formulation = EVSS_F

Polymer Weight Function = GALERKIN

Polymer Viscosity = CONSTANT 1.

Polymer Time Constant = CONSTANT 0.02

Polymer Yield Stress = CONSTANT 15.

Yield Exponent = CONSTANT 0.

The following is a sample card that sets the polymer constitutive equation to SARAMITO_GIESEKUS. This option requires seven cards describing the polymer stress formulation, weight function, viscosity, time constant, mobility parameter, yield stress, and yield exponent.

Polymer Constitutive Equation = SARAMITO_GIESEKUS

Polymer Stress Formulation = EVSS_F

Polymer Weight Function = GALERKIN

Polymer Viscosity = CONSTANT 1.

Polymer Time Constant = CONSTANT 0.2

Polymer Yield Stress = CONSTANT 12.

Yield Exponent = CONSTANT 1.0

Mobility Parameter = CONSTANT 0.1

The following is a sample card that sets the polymer constitutive equation to SARAMITO_PTT. This option requires eight additional cards that set the polymer stress formulation, weight function for the stress equation, viscosity, time constant, nonlinear PTT parameters, yield stress, and yield exponent.

Polymer Consitutive Equation = SARAMITO_PTT

Polymer Stress Formulation = EVSS_F

Polymer Weight Function = GALERKIN

Polymer Viscosity = CONSTANT 8000.

Polymer Time Constant = CONSTANT 0.01

Polymer Yield Stress = CONSTANT 200.

Yield Exponent = CONSTANT 0.5

PTT Xi parameter = CONSTANT 0.10

PTT Epsilon parameter = CONSTANT 0.05

The following is a sample card that sets the polymer constitutive equation to WHITE_METZNER. This option is not currently functional for multimode viscoelasticity. If needed it could be resurrected with only minimal changes to the input parser.

Polymer Consitutive Equation = WHITE_METZNER

Technical Discussion

The viscoelastic tutorial is helpful for usage issues such as extensions from single mode to multimodes.

References

GT-014.1: Tutorial for Running Viscoelastic Flow Problems with GOMA, June 21, 2000, R. R. Rao