Lift force in chiral, compressible granular matter.

Area of Science:

• Physics
• Fluid Dynamics
• Materials Science

Background:

• Micropolar fluid theory extends classical fluid dynamics to include rotational effects.
• Granular flows are complex systems often driven far from equilibrium.
• Traditional models may not fully capture the emergent properties of chiral granular matter.

Purpose of the Study:

• To develop a macroscopic model for granular matter using micropolar fluid dynamics.
• To investigate lift forces in chiral granular flows, considering odd viscosity and microrotation.
• To provide a symmetry-informed continuum description for nonequilibrium granular systems.

Main Methods:

• Formulating a macroscopic micropolar fluid model incorporating internal rotations, couple stresses, and odd viscosity.
• Analyzing steady states in compressible, parity-breaking granular flows, neglecting energy conservation.
• Employing analytical solutions in the linearized Stokes regime and nonlinear finite-element simulations.

Main Results:

• Demonstrated that micropolar fluid dynamics can describe chiral granular flows.
• Quantified the influence of odd viscosity and microrotation on transverse lift forces.
• Showcased the emergence of unique lift forces due to odd transport effects.

Conclusions:

• Micropolar fluid theory offers a physically consistent framework for chiral granular matter.
• The model captures essential features of nonequilibrium granular systems.
• Odd transport effects are crucial for understanding lift phenomena in these flows.