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D. Toneian, G. Kahl, G. Gompper, R. G. Winkler:
"Simulating multi-scale non-Newtonian fluid systems with generalized MPC";
Poster: 4th International Soft Matter Conference 2016 (ISMC 2016), Grenoble, Frankreich; 12.09.2016 - 16.09.2016.

Complex fluids, such as polymer solutions, are often not purely viscous in nature, but rather viscoelastic, i.e. non-Newtonian. To account for the elastic aspects, an extension of the Multiparticle Collision Dynamics (MPC) technique [1,2] has been proposed [3,4], where pairs of MPC particles are connected by springs to form dumbbells. In this work, we generalize this approach to polymers of arbitrary length, and analyze the resulting fluid characteristics. In particular, we measure the transverse component $\tilde{C}_v^T \left( t \right) = \left< \vec{v}^T \left(\vec{k} , t \right) \cdot \vec{v}^T \left(\vec{k} , 0 \right) \cdot \right>$ of the Fourier-space velocity autocorrelation function. We observe that its exponential decay - which is related to an effective fluid viscosity - is superimposed with oscillations, the frequencies of which depend on the relaxation times inherent to the model polymers. We derive an expression for $\tilde{C}_v^T \left( t \right)$ from continuum theory, explain the relationship between model parameters and fluid behavior, and show how the latter can be tuned by adjusting the former. Furthermore, we demonstrate remarkable agreement of the theoretical prediction with simulation data on qualitative and quantitative levels [5].

Projektleitung Gerhard Kahl:
DFS