arXiv subjects

Mahendra Verma

Publications and source records attributed to Mahendra Verma.

2 recordsLinked to original sources

arXiv2025

Turbulence: A Nonequilibrium Field Theory

Tools of quantum and statistical field theories have been successfully ported to turbulence. Here, we review the key results of turbulence field theory. \textit{Equilibrium field theory} describes thermalized spectrally-truncated Euler equation, where the equipartitioned Fourier modes generate zero energy flux. In contrast, \textit{nonequilibrium field theory} is employed for modelling of hydrodynamic turbulence (HDT), which has small viscosity. In HDT, viscosity renormalization yields wavenumber-dependent viscosity and energy spectrum. Field theory calculations also yields nonzero energy flux for HDT. These field theory computations have been generalized to other systems, e.g., passive scalar and magnetohydrodynamics. In this review, I cover these aspects, along with a brief coverage of weak turbulence and intermittency.

cond-mat.stat-mech↗

arXiv2024

Hydrodynamic energy flux in a many-particle system

In this letter, using energy transfers, we demonstrate a route to thermalization in an isolated ensemble of realistic gas particles. We performed a grid-free classical molecular dynamics simulation of two-dimensional Lenard-Jones gas. We start our simulation with a large-scale vortex akin to a hydrodynamic flow and study its non-equilibrium behavior till it attains thermal equilibrium. In the intermediate phases, small wavenumbers ($k$) exhibit $E(k) \propto k^{-3}$ kinetic energy spectrum whereas large wavenumbers exhibit $E(k) \propto k$ spectrum. Asymptotically, $E(k) \propto k$ for the whole range of $k$, thus indicating thermalization. These results are akin to those of Euler turbulence despite complex collisions and interactions among the particles.

physics.flu-dyn↗