Fachgebiet Computersimulationen und Theorie komplexer Fluide

8 Items

Recent Submissions
Manipulating shear-induced non-equilibrium transitions in colloidal films by feedback control

Vezirov, Tarlan A. ; Gerloff, Sascha ; Klapp, Sabine H. L. (2015)

Using Brownian Dynamics (BD) simulations we investigate non-equilibrium transitions of sheared colloidal films under controlled shear stress sigma(xz). In our approach the shear rate (gamma) over dot is a dynamical variable, which relaxes on a time scale tau(c) such that the instantaneous, configuration-dependent stress sigma(xz)(t) approaches a pre-imposed value. Investigating the dynamics und...

Tunable structures of mixtures of magnetic particles in liquid-crystalline matrices

Peroukidis, Stavros D. ; Lichtner, Ken ; Klapp, Sabine H. L. (2015)

We investigate the self-organization of a binary mixture of similar sized rods and dipolar soft spheres by means of Monte-Carlo simulations. We model interparticle interactions by employing anisotropic Gay-Berne, dipolar and soft-sphere interactions. In the limit of vanishing magnetic moments we obtain a variety of fully miscible liquid crystalline phases including nematic, smectic and lamellar...

Generic model for tunable colloidal aggregation in multidirectional fields

Kogler, Florian ; Velev, Orlin D. ; Hall, Carol K. ; Klapp, Sabine H. L. (2015)

Based on Brownian Dynamics computer simulations in two dimensions we investigate aggregation scenarios of colloidal particles with directional interactions induced by multiple external fields. To this end we propose a model which allows continuous change in the particle interactions from point-dipole-like to patchy-like (with four patches). We show that, as a result of this change, the non-equi...

Effects of magnetic field gradients on the aggregation dynamics of colloidal magnetic nanoparticles

Heinrich, Dirk ; Goñi, Alejandro R. ; Osán, Tristán ; Cerioni, L. M. C. ; Smessaert, Anton ; Klapp, Sabine H. L. ; Faraudo, Jordi ; Pusiol, Daniel Jose ; Thomsen, Christian (2015)

We have used low-field H-1 nuclear-magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) to investigate the aggregation dynamics of magnetic particles in ionic ferrofluids (IFFs) in the presence of magnetic field gradients. At the beginning of the experiments, the measured NMR spectra were broad and asymmetric, exhibiting two features attributed to different dynamical environments o...

Self-assembly of three-dimensional ensembles of magnetic particles with laterally shifted dipoles

Yener, Arzu B. ; Klapp, Sabine H. L. (2016)

We consider a model of colloidal spherical particles carrying a permanent dipole moment which is laterally shifted out of the particles' geometrical centres, i.e. the dipole vector is oriented perpendicular to the radius of the particles. Varying the shift delta from the centre, we analyse ground state structures for two, three and four hard spheres, using a simulated annealing procedure. We al...

The effect of charge separation on the phase behavior of dipolar colloidal rods

Rutkowski, David M. ; Velev, Orlin D. ; Klapp, Sabine H. L. ; Hall, Carol K. (2016)

Colloids with anisotropic shape and charge distribution can assemble into a variety of structures that could find use as novel materials for optical, photonic, electronic and structural applications. Because experimental characterization of the many possible types of multi-shape and multipolar colloidal particles that could form useful structures is difficult, the search for novel colloidal mat...

Orientational order and translational dynamics of magnetic particle assemblies in liquid crystals

Peroukidis, Stavros D. ; Klapp, Sabine H. L. (2016)

Implementing extensive molecular dynamics simulations we explore the organization of magnetic particle assemblies (clusters) in a uniaxial liquid crystalline matrix comprised of rodlike particles. The magnetic particles are modelled as soft dipolar spheres with diameter significantly smaller than the width of the rods. Depending on the dipolar strength coupling the magnetic particles arrange in...

Multidirectional colloidal assembly in concurrent electric and magnetic fields

Bharti, Bhuvnesh ; Kogler, Florian ; Hall, Carol K. ; Klapp, Sabine H. L. ; Velev, Orlin D. (2016)

Dipolar interactions between nano- and micron sized colloids lead to their assembly into domains with well-defined local order. The particles with a single dipole induced by an external field assemble into linear chains and clusters. However, to achieve the formation of multidirectionally organized nano-or microassemblies with tunable physical characteristics, more sophisticated interaction too...