15,268 research outputs found
Numerical simulation of single droplet dynamics in three-phase flows using ISPH
In this study, a new surface tension formulation for modeling incompressible, immiscible three-phase fluid flows in the context of incompressible smoothed particle hydrodynamics (ISPH) in two dimensions has been proposed. A continuum surface force model is employed to transform local surface tension force to a volumetric force while physical surface tension coefficients are expressed as the sum of phase specific surface tension coefficients, facilitating the implementation of the proposed method at triple junctions where all three phases are present. Smoothed color functions at fluid interfaces along with artificial particle displacement throughout the computational domain are combined to increase accuracy and robustness of the model. In order to illustrate the effectiveness of the proposed method, several numerical simulations have been carried out and results are compared to analytical data available in literature. Results obtained by simulations are compatible with analytical data, demonstrating that the ISPH scheme proposed here is capable of handling three-phase flows accurately
Numerical simulation of super-square patterns in Faraday waves
We report the first simulations of the Faraday instability using the full
three-dimensional Navier-Stokes equations in domains much larger than the
characteristic wavelength of the pattern. We use a massively parallel code
based on a hybrid Front-Tracking/Level-set algorithm for Lagrangian tracking of
arbitrarily deformable phase interfaces. Simulations performed in rectangular
and cylindrical domains yield complex patterns. In particular, a
superlattice-like pattern similar to those of [Douady & Fauve, Europhys. Lett.
6, 221-226 (1988); Douady, J. Fluid Mech. 221, 383-409 (1990)] is observed. The
pattern consists of the superposition of two square superlattices. We
conjecture that such patterns are widespread if the square container is large
compared to the critical wavelength. In the cylinder, pentagonal cells near the
outer wall allow a square-wave pattern to be accommodated in the center
Faraday instability on a sphere: numerical simulation
We consider a spherical variant of the Faraday problem, in which a spherical
drop is subjected to a time-periodic body force, as well as surface tension. We
use a full three-dimensional parallel front-tracking code to calculate the
interface motion of the parametrically forced oscillating viscous drop, as well
as the velocity field inside and outside the drop. Forcing frequencies are
chosen so as to excite spherical harmonic wavenumbers ranging from 1 to 6. We
excite gravity waves for wavenumbers 1 and 2 and observe translational and
oblate-prolate oscillation, respectively. For wavenumbers 3 to 6, we excite
capillary waves and observe patterns analogous to the Platonic solids. For low
viscosity, both subharmonic and harmonic responses are accessible. The patterns
arising in each case are interpreted in the context of the theory of pattern
formation with spherical symmetry
Coupled DEM-LBM method for the free-surface simulation of heterogeneous suspensions
The complexity of the interactions between the constituent granular and
liquid phases of a suspension requires an adequate treatment of the
constituents themselves. A promising way for numerical simulations of such
systems is given by hybrid computational frameworks. This is naturally done,
when the Lagrangian description of particle dynamics of the granular phase
finds a correspondence in the fluid description. In this work we employ
extensions of the Lattice-Boltzmann Method for non-Newtonian rheology, free
surfaces, and moving boundaries. The models allows for a full coupling of the
phases, but in a simplified way. An experimental validation is given by an
example of gravity driven flow of a particle suspension
Simplex space-time meshes in thermally coupled two-phase flow simulations of mold filling
The quality of plastic parts produced through injection molding depends on
many factors. Especially during the filling stage, defects such as weld lines,
burrs, or insufficient filling can occur. Numerical methods need to be employed
to improve product quality by means of predicting and simulating the injection
molding process. In the current work, a highly viscous incompressible
non-isothermal two-phase flow is simulated, which takes place during the cavity
filling. The injected melt exhibits a shear-thinning behavior, which is
described by the Carreau-WLF model. Besides that, a novel discretization method
is used in the context of 4D simplex space-time grids [2]. This method allows
for local temporal refinement in the vicinity of, e.g., the evolving front of
the melt [10]. Utilizing such an adaptive refinement can lead to locally
improved numerical accuracy while maintaining the highest possible
computational efficiency in the remaining of the domain. For demonstration
purposes, a set of 2D and 3D benchmark cases, that involve the filling of
various cavities with a distributor, are presented.Comment: 14 pages, 11 Figures, 4 Table
- âŠ