1,590 research outputs found
Liquid-gas-solid flows with lattice Boltzmann: Simulation of floating bodies
This paper presents a model for the simulation of liquid-gas-solid flows by
means of the lattice Boltzmann method. The approach is built upon previous
works for the simulation of liquid-solid particle suspensions on the one hand,
and on a liquid-gas free surface model on the other. We show how the two
approaches can be unified by a novel set of dynamic cell conversion rules. For
evaluation, we concentrate on the rotational stability of non-spherical rigid
bodies floating on a plane water surface - a classical hydrostatic problem
known from naval architecture. We show the consistency of our method in this
kind of flows and obtain convergence towards the ideal solution for the
measured heeling stability of a floating box.Comment: 22 pages, Preprint submitted to Computers and Mathematics with
Applications Special Issue ICMMES 2011, Proceedings of the Eighth
International Conference for Mesoscopic Methods in Engineering and Scienc
Lattice Boltzmann simulations of soft matter systems
This article concerns numerical simulations of the dynamics of particles
immersed in a continuum solvent. As prototypical systems, we consider colloidal
dispersions of spherical particles and solutions of uncharged polymers. After a
brief explanation of the concept of hydrodynamic interactions, we give a
general overview over the various simulation methods that have been developed
to cope with the resulting computational problems. We then focus on the
approach we have developed, which couples a system of particles to a lattice
Boltzmann model representing the solvent degrees of freedom. The standard D3Q19
lattice Boltzmann model is derived and explained in depth, followed by a
detailed discussion of complementary methods for the coupling of solvent and
solute. Colloidal dispersions are best described in terms of extended particles
with appropriate boundary conditions at the surfaces, while particles with
internal degrees of freedom are easier to simulate as an arrangement of mass
points with frictional coupling to the solvent. In both cases, particular care
has been taken to simulate thermal fluctuations in a consistent way. The
usefulness of this methodology is illustrated by studies from our own research,
where the dynamics of colloidal and polymeric systems has been investigated in
both equilibrium and nonequilibrium situations.Comment: Review article, submitted to Advances in Polymer Science. 16 figures,
76 page
Elastic response of a nematic liquid crystal to an immersed nanowire
We study the immersion of a ferromagnetic nanowire within a nematic liquid
crystal using a lattice Boltzmann algorithm to solve the full three-dimensional
equations of hydrodynamics. We present an algorithm for including a moving
boundary, to simulate a nanowire, in a lattice Boltzmann simulation. The
nematic imposes a torque on a wire that increases linearly with the angle
between the wire and the equilibrium direction of the director field. By
rotation of these nanowires, one can determine the elastic constants of the
nematic.Comment: 10 pages, 8 figure
Instability and treatments of the coupled discrete element and lattice Boltzmann method by the immersed moving boundary scheme
The immersed moving boundary (IMB) scheme has been extensively used to couple the discrete element method (DEM) with the lattice Boltzmann method (LBM). In the literature, only the formulation of IMB for lattice nodal cells covered by a singleâsolid particle was given. The treatment of situations where a nodal cell is covered by two or more solid particles is seldom discussed. It is found that some numerical instability can occur for such situations due to an inappropriate computation of the weighting function in the IMB formulation. This work presents an enhanced treatment that can resolve the issue and validates it using some benchmark tests. Furthermore, to avoid the extra costs associated with the treatment and simplify the complicated procedure introduced, a simplified IMB scheme is proposed. The accuracy of both enhanced and simplified IMB schemes are validated by test cases including singleâparticle sedimentation, twoâparticle draftingâkissingâtumbling phenomenon, and multipleâparticle sedimentation. Then, the robustness of both schemes is examined and discussed using a specially designed flow past cylinders test. The simplified IMB scheme is proved to be robust and sufficiently accurate and simpler and more effective than the enhanced scheme
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