Velocity field and particle position during the sedimentation of 30 circular particles. The white lines stand for the streamlines, while the arrows indicate the flow direction. The simulation was performed on a 540 × 1024 grid.
Dendrites descending in viscous fluid (upper row) with initial orientation “+”, and (bottom row) with initial orientation “×” at downward gravitational acceleration 0.001g. Note the stable behavior until hydrodynamic interaction with the lower wall of the simulation box intervenes, which makes the dendritic particle tumble (see upper row). The simulations were performed on a 4000×5000 grid.
Velocity and concentration fields (upper and bottom rows, respectively) with streamlines during the sedimentation of dendritic particles in viscous fluid and gravity of 0.001g. The simulation was performed on a 2000 × 2000 grid.
Velocity and concentration fields (upper and bottom rows, respectively) during CET via columnar growth from the bottom and nucleation in the upper domain of the simulation box. The simulation was performed on a 4096 × 3072 grid.
Velocity (upper row) and concentration fields (bottom row) during CET induced by a “plume” (a process shown in Fig. 1). The flow in the plume is represented by a wall moving upward. Simulation performed on a 6016 × 4000 grid.
The concentration field map of the mineral component (bright yellow denotes high concentration of the mineral component, whereas blue indicates the organic reach domains) during the directional solidification of a shell model as predicted by the orientation field based phase-field simulation under the same conditions as the simulation shown in Fig. 7, however, using a larger grid of 2000 × 1000. The black domain on the right represents the mantle.
The orientation field map (different colors stand for different crystallographic orientations) during the directional solidification of a shell model as predicted by the orientation field based phase-field simulation under the same conditions as the simulation shown in Fig. 7, however, using a larger grid of 2000 × 1000. The white domain on the right represents the mantle.
Shell morphology as predicted by two-dimensional phase-field simulation under decreasing supersaturation. Concentration map: light gray –calcium carbonate rich, dark gray –organic-component-rich. Note that the prisms are formed from eight nucleation events: the borders between such areas are indicated by lines of organic-component-rich solid. Orientation map: black –fluid, different colors stand for different crystallographic orientations.
Structural aspects of crystal nucleation in undercooled liquids are explored using a nonlinear hydrodynamic theory of crystallization proposed recently [G. I. Tóth et al., J. Phys.: Condens. Matter 26, 055001 (2014)], which is based on combining fluctuating hydrodynamics with the phase-field crystal theory. We show that in this hydrodynamic approach not only homogeneous and heterogeneous nucleation processes are accessible, but also growth front nucleation, which leads to the formation of new (differently oriented) grains at the solid-liquid front in highly undercooled systems. Formation of dislocations at the solid-liquid interface and interference of density waves ahead of the crystallization front are responsible for the appearance of the new orientations at the growth front that lead to spherulite-like nanostructures.
Article: Physical Review E 95, 052801, (2017)
Slide No. 1:
Polycrystalline solidification in the HPFC model supplemented with momentum noise within the metastable (ϵ < ϵc) and unstable liquid (ϵ > ϵc) regimes. Here ϵc = 0.1178 is the linear stability limit of the liquid phase, and ψ0 = −0.1982 is the initial density of the liquid. Note that in all cases, crystallization was started by placing a single potential well of the atomic size at the center of the simulation box. The time elapsed between subsequent snapshots was 10000 timesteps for the upper and central rows, whereas 50000 timesteps for the bottom row.
Slide No. 2:
Polycrystalline growth in the HPFC model: Two mechanisms are observed for creating new orientations at the solidification front: (a) nucleation of dislocations preferably in cusps of the interface and (b) nucleation near the front due to density waves emanating from the solid-liquid interface. The right and the lower side of the roughly hexagonal crystal (displayed in the red rimmed insert) are shown magnified in the upper and lower rows of the animations,