Spectral energy scaling in precessing turbulence.

Area of Science:

• Geophysics and Astrophysics
• Fluid Dynamics

Background:

• Precessing turbulence is observed in geophysical and astrophysical systems.
• Understanding its dynamics is crucial for modeling complex flows.

Purpose of the Study:

• To investigate the dynamics of precessing turbulence using direct numerical simulations.
• To characterize the energy evolution and spectral properties of this turbulent flow.

Main Methods:

• Direct numerical simulations of homogeneous turbulence.
• Imposition of a background flow to trigger precessional instability.
• Analysis of kinetic energy evolution and spectral scaling.

Main Results:

• Identified two distinct phases in kinetic energy development: exponential growth and nonlinear saturation.
• Observed a transition to quasi-two-dimensional flow during saturation.
• Demonstrated a kinetic energy spectrum scaling of k^{-3} in the k_{∥}=0 plane for saturated flows, consistent with other rotating systems.

Conclusions:

• Precessing turbulence exhibits distinct dynamical phases with characteristic flow topologies.
• The saturated state shows spectral properties similar to other quasi-two-dimensional rotating flows.
• Identified specific wave number ranges (between Zeman scales) where power-law scaling is observed.