Microstructural evolution in drying colloidal films driven by evaporation and sedimentation: lattice Boltzmann...

Area of Science:

• Materials Science
• Fluid Dynamics
• Computational Physics

Background:

• Colloidal film properties are crucial for applications.
• Understanding particle dynamics during drying is key to controlling film microstructure.
• Previous models often lack detailed consideration of competing evaporation and sedimentation effects.

Purpose of the Study:

• To investigate colloidal particle dynamics during vertical drying.
• To identify key parameters governing particle distribution and film formation.
• To develop a predictive model for colloidal film drying.

Main Methods:

• Utilizing the lattice Boltzmann method for simulations.
• Developing a one-dimensional mathematical drying model.
• Analyzing particle accumulation and crystallization phenomena.

Main Results:

• Particle distribution is governed by the drying Péclet number (Pe) and sedimentation Péclet number (Pe_sed).
• High evaporation rates (Pe ≫ Pe_sed) lead to top-layer accumulation and crystallization.
• Dominant sedimentation (Pe ≪ Pe_sed) results in bottom-layer accumulation and crystallization.
• The developed model quantitatively matches simulation results across various Pe and Pe_sed values.

Conclusions:

• Drying and sedimentation dynamics critically influence colloidal film microstructural quality.
• New drying regime maps are established, defining evaporation, diffusion, and sedimentation-dominated regions.
• The findings provide a framework for optimizing colloidal film fabrication.