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@PHDTHESIS{Alekseeva:154742,
author = {Alekseeva, Uliana},
title = {{A}daptive {R}esolution {S}imulations: {C}ombining
{M}ulti-{P}article-{C}ollision {D}ynamics and {M}olecular
{D}ynamics {S}imulations for {F}luids},
school = {RWTH Aachen},
type = {Dissertation},
reportid = {FZJ-2014-04022},
pages = {115 p.},
year = {2014},
note = {Dissertation, RWTH Aachen, 2014},
abstract = {In soft matter physics there is a variety of systems where
phenomena occur on different time- and length scales which
are inherently coupled. Examples of such systems are
colloidal suspensions, polymer solutions or biological
macromolecules. To simulate such systems, it is necessary to
consistently take into account atomistic and hydrodynamic
interactions within one computational scheme, which is
feasible from the requirements of memory consumption and CPU
time usage. The hybrid simulation approach presented in this
work solves this problem by coupling of Molecular Dynamics
and Multi-Particle Collision dynamics simulations. It allows
to change the representation of the molecules composing the
fluid "on the fly", taking into account the atomistic
details where it is needed, while keeping the description of
the rest of the fluid on the mesoscale level. Due to the
application of such hybrid coupling between fine- and
coarse-grained description, it is possible to simulate
larger systems for longer times efficiently, while taking
into account solvent properties and hydrodynamics.The main
goal of this work is to construct a hybrid description of
the solvent in such a way that hydrodynamic interactions are
properly accounted for. To reveal the hydrodynamic
properties of the hybrid fluid, a number of correlations
functions for various systems with different hybrid states
were calculated. It was found that transverse current
correlation functions related to the viscosity coefficient
are equal for all states of the fluid, i.e. "pure" MD,
"pure" MPC and all "mixed state" systems. The same applies
to the properties of long tile tails in the velocity
autocorrelation function, which is influencing the diffusion
coefficient of the fluid. Therefore, these results show that
the transport properties of the fluid are not altered
throughout the hybrid description. In order to verify that
hydrodynamics is maintained in the hybrid system, several
test flow simulations such as Poiseuille flow, shear flow,
and Couette flow were performed. They have shown that the
behavior of the hybrid system under flow resembles that of a
fluid modeled by a mono-scale method, and it could be shown
that the deviation of the velocity profile from the
theoretically predicted one is less than $2\\%.Although$ the
full thermodynamic equilibrium is impossible due the
fundamental differences between MD and MPC methods, the
hybrid MD/MPC scheme presented in this work is proved to be
a very promising approach for simulation of complex fluids.
By applying the restraining force in the buffer zone it is
possible to maintain dynamical equilibrium throughout the
hybrid system. It was shown that the transport properties of
the hybrid fluid are conserved across the transition zone
between the two fluid representations in one simulation,
allowing the consistent description of hydrodynamics in the
whole coupled system. By changing the representation of the
molecules Òon the flyÓ, the hybrid MD/MPC approach allows
to couple within a single simulation atomistic and mesoscale
representation of fluids, providing a valuable tool for many
problems in soft matter science.},
keywords = {Dissertation (GND)},
cin = {JSC},
cid = {I:(DE-Juel1)JSC-20090406},
pnm = {899 - ohne Topic (POF2-899)},
pid = {G:(DE-HGF)POF2-899},
typ = {PUB:(DE-HGF)11},
url = {https://juser.fz-juelich.de/record/154742},
}