Lattice Boltzmann scheme for crystal growth in external flows

Area of Science:

• Materials Science
• Computational Physics
• Fluid Dynamics

Background:

• Dendritic growth is crucial in materials science, influenced by heat transport and fluid flow.
• Understanding crystal morphology under various conditions is essential for controlling material properties.

Purpose of the Study:

• To simulate and analyze dendritic and doublon growth from a supercooled melt.
• To investigate the impact of shear and parallel flows on crystal growth dynamics.
• To complement selection theories by measuring dendrite tip behavior under flow.

Main Methods:

• A composite phase-field lattice-Boltzmann scheme was employed.
• The phase-field approach modeled phase transitions, while lattice-Boltzmann-BGK (Bhatnagar, Gross, and Krook) simulated liquid flow with thermal convection.
• Multicomponent lattice-Boltzmann methods handled heat transport.

Main Results:

• Simulations produced dendrites or doublons based on anisotropy and undercooling.
• Doublons exhibited robust behavior and distinct dynamics in shear flow compared to dendrites.
• Parallel flow influenced dendrite tip states, showing power-law dependencies for intermediate undercoolings.
• High flow velocities induced tip oscillations and coherent side branch generation in dendrites.

Conclusions:

• The phase-field lattice-Boltzmann method effectively simulates complex crystal growth phenomena.
• Doublons present unique stability and dynamic characteristics in flowing melts.
• Flow conditions significantly alter dendrite morphology and growth, offering insights into pattern selection.