Forced two-dimensional turbulence in spectral and physical space

Area of Science:

• Fluid Dynamics
• Turbulence Theory
• Computational Physics

Background:

• Two-dimensional (2D) turbulence displays nonuniversal characteristics in its energy range.
• Observed deviations include departures from the k(-5/3) energy spectrum law at low wavenumbers (k).
• Nonuniversal features also manifest as variable energy flux and irregular, nonlocal energy transfers.

Purpose of the Study:

• To investigate the underlying mechanisms responsible for nonuniversal behavior in 2D turbulence.
• To analyze the complex multiscale organization of the vorticity field and associated dynamic processes.
• To identify and characterize the role of localized vortices in 2D turbulence.

Main Methods:

• Conducted detailed numerical simulations of 2D turbulence.
• Utilized a 512 grid resolution for simulations.
• Examined turbulence under varying forcing-dissipation conditions.
• Analyzed data in both spectral and physical spaces.

Main Results:

• Revealed a complex multiscale organization within the vorticity field.
• Identified dynamic processes ranging from large-scale meandering jets to strong localized vortices.
• Determined that localized vortices are primarily responsible for the nonuniversal behavior.
• Examined the statistical features and growth mechanisms of these localized vortices.

Conclusions:

• Localized vortices are key drivers of nonuniversal phenomena in 2D turbulence.
• Understanding these vortices is crucial for a complete theory of 2D turbulent energy transfer.
• The study provides insights into the statistical properties and formation of these structures.