Behavior of viscoelastic models with thermal fluctuations

Area of Science:

• Polymer physics
• Rheology
• Computational fluid dynamics

Background:

• Viscoelastic models are crucial for describing polymer dynamics.
• Understanding the influence of thermal fluctuations is key for accurate modeling.
• Conformation-tensor-based models are widely used but require validation.

Purpose of the Study:

• To investigate the impact of fluctuating viscoelasticity on conformation-tensor-based models.
• To compare the behavior of the upper-convected Maxwell, FENE-P, and Giesekus models under varying thermal fluctuation strengths.
• To analyze model responses in equilibrium, simple shear, and uniaxial extension deformations.

Main Methods:

• Numerical simulations were employed to study three viscoelastic models: upper-convected Maxwell, FENE-P, and Giesekus.
• Models were compared against each other and analytical predictions for the Maxwell model.
• Simulations covered equilibrium, simple shear, and uniaxial extension conditions.

Main Results:

• At equilibrium, all models exhibited marginal differences in static and dynamic characteristics.
• In deformation, Maxwell model's average response was insensitive to thermal fluctuations.
• FENE-P and Giesekus models showed a slight decrease in mechanical response with increased fluctuations, particularly in simple shear.

Conclusions:

• Thermal fluctuations have a noticeable effect on FENE-P and Giesekus models, but not the Maxwell model, during deformation.
• The standard deviation of the mechanical response increases with fluctuation strength for all models.
• Deformation strength reduces the relative standard deviation, with a more pronounced effect in uniaxial extension than simple shear.