********************** Polymer Shift Function ********************** :: Polymer Shift Function = {CONSTANT | MODIFIED_WLF} [float2] ----------------------- **Description / Usage** ----------------------- This optional card is used to specify the temperature shift function for the polymer relaxation times and viscosities in the polymer stress equation(s); .. figure:: /figures/391_goma_physics.png :align: center :width: 90% Valid options are +-----------------+------------------------------------------------------------------------------------------------------------+ |**CONSTANT** |Applies a constant temperature shift factor to the polymer relaxation time(s) and the polymer viscosities. | | | | | | * - the temperature shift factor. If this card is not present, this option is the default and a | | | shift factor of 1.0 is applied. | +-----------------+------------------------------------------------------------------------------------------------------------+ This option may be useful for continuation in elasticity level since continuation in this parameter will uniformly increase or decrease the relaxation time(s) and viscosities of all viscoelastic modes. +-----------------+------------------------------------------------------------------------------------------------------------+ |**MODIFIED_WLF** |Applies a temperature shift factor which is a modified version of the Williams-Landel-Ferry shift model (cf.| | |Bird, Armstrong, and Hassager 1987, pp.139-143); | | | | | |.. figure:: /figures/392_goma_physics.png | | | :align: center | | | :width: 90% | | | | | |The reference temperature, Tref, is taken from the Reference Temperature card. Note that if C2 is chosen | | |equal to Tref, this model reduces to an Arrhenius form where C1 = Eμ/RTref. Also note that this form is | | |based on the exponential function whereas the WLF model is based on 10x. | | | | | | * - constant C1 | | | | | | * - constant C2 | +-----------------+------------------------------------------------------------------------------------------------------------+ ------------ **Examples** ------------ The following is a sample card that sets a constant temperature shift. :: Polymer Shift Function = CONSTANT 1.0 The following is a sample card that utilizes the modified WLF shift function. :: Polymer Shift Function = MODIFIED_WLF 2.5 95.0 ------------------------- **Technical Discussion** ------------------------- No Discussion. -------------- **References** -------------- Bird, R. B., Armstrong, R. C., and Hassager, O. Dynamics of Polymeric Liquids, Volume 1. John Wiley & Sons, Inc. 1987.