title: Fully developed isotropic turbulence: Nonperturbative renormalization group formalism and fixed-point solution.
abstract: We investigate the regime of fully developed homogeneous and isotropic turbulence of the Navier-Stokes (NS) equation in the presence of a stochastic forcing, using the nonperturbative (functional) renormalization group (NPRG). Within a simple approximation based on symmetries, we obtain the fixed-point solution of the NPRG flow equations that corresponds to fully developed turbulence both in d=2 and 3 dimensions. Deviations to the dimensional scalings (Kolmogorov in d=3 or Kraichnan-Batchelor in d=2) are found for the two-point functions. To further analyze these deviations, we derive exact flow equations in the large wave-number limit, and show that the fixed point does not entail the usual scale invariance, thereby identifying the mechanism for the emergence of intermittency within the NPRG framework. The purpose of this work is to provide a detailed basis for NPRG studies of NS turbulence; the determination of the ensuing intermittency exponents is left for future work.
authors.affiliation: LPMMC, Université Joseph Fourier Grenoble-Alpes, CNRS UMR 5493, 38042 Grenoble Cedex, France.
authors.forename: Léonie
authors.initials: L
authors.lastname: Canet
authors.affiliation: LPTMC, CNRS UMR 7600, Université Pierre et Marie Curie, 75252 Paris Cedex 05, France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Delamotte
authors.affiliation: LPTMC, CNRS UMR 7600, Université Pierre et Marie Curie, 75252 Paris Cedex 05, France.|Instituto de Física, Facultad de Ingeniería, Universidad de la República, J.H.y Reissig 565, 11000 Montevideo, Uruguay.
authors.forename: Nicolás
authors.initials: N
authors.lastname: Wschebor