Acceleration of Lagrangian particles in shell models of turbulence

Extreme Lagrangian acceleration in turbulence is often attributed to particle trapping in coherent vortex structures. Here, we show that shell models, despite lacking vortex filaments, reproduce the extreme intermittent fluctuations of Lagrangian acceleration seen in real flows. Within the multifractal framework, we accurately predict acceleration moments and full probability distribution functions (PDFs) across a wide range of Reynolds numbers. This shows extreme Lagrangian fluctuations can arise from inertial-range dynamics alone, supporting the universality of multifractal statistics and highlighting shell models as effective tools to capture key features of turbulence.