Vorträge und Posterpräsentationen (ohne Tagungsband-Eintrag):
D. Toneian, G. Kahl, G. Gompper, R. G. Winkler:
"Multiparticle collision dynamics simulations of viscoelastic fluids: Time correlation functions";
Vortrag: 24th International Conference on Discrete Simulation of Fluid Dynamics,
Edinburgh, United Kingdom;
13.07.2015
- 17.07.2015.
Kurzfassung englisch:
Complex fluids, such as polymer solutions and melts, are often viscoelastic rather than purely viscose. To capture viscoelastic properties in computer simulations, an efficient and simple description for the fluid is desirable and is achieved by mesoscale simulation techniques. Recently, computationally efficient extensions of the multiparticle collision dynamics (MPC) approach to viscoelastic fluids have been proposed [1, 2], where two MPC particles are combined into a dumbbell.
Here, we present an extension of these studies to (short) polymers with N=3 and 10 constituent fluid particles. We analyze the center-of-mass velocity autocorrelation function of dumbbells, trimers, and decamers, characterizing their hydrodynamic and viscoelastic properties. In Fourier space, the transverse velocity-correlation function CT(k,t) ~ <vT(k,t) * vT(-k,0)> exhibits oscillations superimposed with an exponential decay, where the oscillation frequency is related to the polymer relaxation time, and the damping to the fluid viscosity. From the known storage and loss moduli of dumbbells, an analytical expression for the correlation function in the case N=2 is derived, which is in quantitative agreement with the simulation results. Further results for the real-space correlation functions will be presented, and the long-time behavior will be discussed.
Having gained a quantitative understanding of this fluid model, its properties can be tuned so as to study complex systems, e.g., polymer melts or viscoelastic fluids containing colloids or microswimmers, which are often found in technical applications and biology.
[1] Tao, Y.-G., Götze, I. O., Gompper, G., Multiparticle collision dynamics modeling of viscoelastic fluids, J. Chem. Phys 128, 144902, 2008.
[2] Kowalik, B., Winkler, R. G., Multiparticle collision dynamics simulations of viscoelastic fluids: Shear-thinning Gaussian dumbbells, J. Chem. Phys. 138, 104903, 2013.
Zugeordnete Projekte:
Projektleitung Gerhard Kahl:
DFS
Erstellt aus der Publikationsdatenbank der Technischen Universität Wien.