Two-fluid model for a fluid with tetrahedral-octupolar order

Area of Science:

• Fluid dynamics
• Condensed matter physics
• Non-equilibrium systems

Background:

• Two-fluid systems possess unique dynamics due to inter-component interactions.
• Tetrahedral order introduces parity symmetry breaking and octupolar order.
• Optically isotropic materials lacking preferred direction are considered.

Purpose of the Study:

• Investigate macroscopic dynamics in two-fluid systems with tetrahedral order.
• Identify and characterize novel reversible and dissipative cross-coupling terms.
• Explore experimental implications of these cross-couplings.

Main Methods:

• Theoretical analysis of macroscopic variables (velocity difference, concentration).
• Examination of parity symmetry breaking due to tetrahedral order.
• Modeling of dynamic cross-coupling terms, including dissipative and reversible types.

Main Results:

• Discovered dissipative cross-coupling between relative velocity and velocity gradients.
• Observed generation of perpendicular velocity differences under planar shear flow, leading to relative velocity oscillations.
• Identified coupling of induced relative velocity with concentration, creating overdamped sound-like modes.
• Demonstrated reversible cross-coupling between electric field gradients and velocity, also inducing overdamped modes.

Conclusions:

• Tetrahedral order in two-fluid systems leads to unique dynamic cross-couplings.
• Dissipative cross-coupling offers experimental avenues for controlling fluid behavior, such as inducing oscillations.
• The findings contribute to understanding complex fluid dynamics and potential applications in optically isotropic materials.