Prof. Ryo ARAKI
Titolo
Energy and information transfer mechanisms in developed turbulence
Abstract
The emergence of the small-scale universality of developed turbulence is often described as the small scales forgetting about the macroscopic flow characteristics during the scale-local energy cascade process. However, its precise mechanism is yet to be understood. To tackle this problem, we attempt to quantify the so-called "information flux" (Lozano-Duran and Arranz, Phys. Rev. Res. 4, 023195 (2022)) in high-Reynolds-number homogeneous and isotropic turbulent flow in a periodic box. This quantity quantifies how the knowledge of the current status of a variable reduces the
uncertainty of the future status of another variable of a dynamical system. Furthermore, we look into different physical mechanisms of the energy cascade: vortex stretching (VS) and strain-self amplification (SSA). More precisely, we decomposed the energy flux into five components according to Johnson, Phys. Rev. Lett. 124, 104501 (2020); Johnson, J. Fluid Mech. 922, A3 (2021). We then calculated the Lagrangian trajectory of the (decomposed) energy flux from the time-resolved turbulence dataset and evaluated the information flux among different scales. We found that the information is transferred locally in scale, and the energy and information transfers are governed by different mechanisms. In other words, the dominant energy transfer mechanism is not the most causal, and vice versa.
During the seminar, I plan to share some ideas to deepen our understanding of turbulence by using tools developed in information theory and information thermodynamics, which is a reconstruction of microscopic thermodynamics by explicitly taking information into account.
References:
- Araki et al., "Forgetfulness of turbulent energy cascade associated with different mechanisms", Journal of Physics:
Conference Series, 2753, 012001 (2024).
- Tanogami and Araki, "Information-thermodynamic bound on information flow in turbulent cascade", Physical Review
Research, 6 013090 (2024).
Poster available at this link.
