Scaling or multiscaling: Varieties of universality in a driven nonlinear model

TL;DR

This paper investigates how symmetries and nonlinear effects influence scaling and multiscaling in driven nonlinear systems, using a hydrodynamic model and renormalization group analysis to reveal various universal behaviors.

Contribution

It introduces a nonlinear hydrodynamic model parametrized by nonlinear coefficients and spatial scaling, and analyzes its multiscaling properties using perturbative renormalization group methods.

Findings

Model exhibits simple scaling and multiscaling depending on parameters

Multiscaling exponents are calculated using one-loop renormalization group

Universal scaling behaviors are identified in driven nonlinear systems

Abstract

Physical understanding of how the interplay between symmetries and nonlinear effects can control the scaling and multiscaling properties in a coupled driven system, such as magnetohydrodynamic turbulence or turbulent binary fluid mixtures, remains elusive till the date. To address this generic issue, we construct a conceptual nonlinear hydrodynamic model, parametrised jointly by the nonlinear coefficients, and the spatial scaling of the variances of the advecting stochastic velocity and the stochastic additive driving force, respectively. By using a perturbative one-loop dynamic renormalisation group method, we calculate the multiscaling exponents of the suitably defined equal-time structure functions of the dynamical variable. We show that depending upon the control parameters the model can display a variety of universal scaling behaviours ranging from simple scaling to multiscaling.