Hydrodynamic correlations of viscoelastic fluids by multiparticle collision dynamics simulations
David Toneian1, Gerhard Kahl1, Gerhard Gompper2
1Institute for Theoretical Physics, TU Wien, Wiedner Hauptstraße 8-10, 1040 Wien, Austria.
The Journal of Chemical Physics
|November 24, 2019
Summary
This study explores viscoelastic fluid dynamics using multiparticle collision dynamics (MPC). Viscoelasticity introduces correlations and unique long-time tails in polymer motion, matching analytical predictions.
Area of Science:
- Fluid dynamics
- Polymer physics
- Computational physics
Background:
- Understanding the hydrodynamics of complex fluids like viscoelastic polymer solutions is crucial.
- The multiparticle collision dynamics (MPC) method offers a mesoscopic approach to simulate such systems.
- Previous models often simplified polymer interactions or neglected fluctuating hydrodynamics.
Purpose of the Study:
- To investigate the emergent fluctuating hydrodynamics of viscoelastic fluids using the MPC method.
- To analyze the influence of polymer length and viscoelasticity on fluid properties.
- To compare simulation results with analytical solutions of the Navier-Stokes equation.
Main Methods:
- Modeling viscoelastic fluids with flexible, Gaussian phantom polymers interacting via stochastic MPCs.
- Calculating the analytical solution of the linearized Navier-Stokes equation with a time-dependent shear relaxation modulus.
- Characterizing fluid properties using transverse velocity autocorrelation functions in Fourier and real space.
Main Results:
- Viscoelasticity induces strong correlations that decay exponentially in Fourier space.
- Individual polymer center-of-mass velocity autocorrelation functions show a length-independent t-3/2 long-time tail.
- Long polymers exhibit an additional negative correlation power-law decay dependent on polymer length (L-1/2).
Conclusions:
- The MPC approach accurately captures the fluctuating hydrodynamics of viscoelastic fluids.
- Polymer length and viscoelasticity significantly alter fluid dynamics, introducing distinct correlation behaviors.
- Simulation and analytical results show good agreement, validating the model and findings.
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