Lagrangian Irreversibility and Energy Exchanges in Rotating-Stratified Turbulent Flows

Area of Science:

• Fluid dynamics
• Turbulence research
• Geophysical flows

Background:

• Stratified and rotating turbulent flows exhibit complex interactions between waves and eddies.
• These interactions drive continuous energy exchanges between potential and kinetic energy forms.

Purpose of the Study:

• To investigate the impact of wave-eddy interplay on the turbulent energy cascade.
• To analyze how these processes influence the irreversible evolution of kinetic energy between tracer particles.

Main Methods:

• Analysis of turbulent energy cascade dynamics.
• Examination of relative kinetic energy evolution between tracer particles at varying separations.
• Identification of characteristic length scales governing energy transfer.

Main Results:

• A characteristic length scale (ℓt) was identified, influencing energy transfer direction based on particle separation (r0).
• When r0 < ℓt, potential energy is transferred to kinetic energy, decreasing irreversibility.
• When r0 > ℓt, the opposite energy transfer occurs, increasing irreversibility.
• The characteristic length scale ℓt was found to coincide with the buoyancy length scale (LB) across many configurations.

Conclusions:

• The study reveals a scale-dependent mechanism controlling energy transfer and irreversibility in stratified and rotating turbulence.
• The buoyancy length scale (LB) plays a crucial role in this energy transfer process.
• A transition to a wave-dominated regime was observed, altering the dynamics beyond a certain scale.