Kishore Dutta | Searcharxiv

arXiv2017

Renormalized cumulants and velocity derivative skewness in Kolmogorov turbulence

We apply a renormalized perturbative scheme on the Navier-Stokes equation for an incompressible isotropic turbulent velocity field. This allows us to obtain the renormalized expressions for second- and third-order cumulants of the velocity derivative directly from the corresponding Feynman diagrams. The resulting expressions are integrated numerically by excluding and including the dissipation range assuming Kolmogorov and Pao's phenomenological expressions for the energy spectrum. The ensuing values for skewness are found to be $S=-0.647$ (when the dissipation range is excluded) and $\mathcal{S}=-0.682$ (when the dissipation is included). These estimated values are compared with various experimental, numerical, and theoretical results.

cond-mat.stat-mech↗

arXiv2016

Reply to Comment on Nonlocal quartic interactions and universality classes in perovskite manganites

Comment [arXiv:cond-mat.stat.mech., 1602.02087v1 (2016)] has raised questions claiming that the nonlocal model Hamiltonian presented in [Phys. Rev. E 92, 012123 (2015)] is equivalent to the standard (short-ranged) Φ^4 theory. These claims are based on a low momentum expansion of the interaction vertex that cannot be applied to the vertex factors containing both low and high momenta inside the loop-integrals. Elaborating upon the important steps of the momentum shell decimation scheme, employed in the renormalization-group calculation, we explicitly show the interplay of internal (high) and external (low) momenta determining the loop integrals for self-energy and vertex functions giving rise to corrections (to the bare parameters) different from those of the standard (short-ranged) Φ^4 theory. Employing explicit mathematical arguments, we show that this difference persists when the range of interaction is assumed to be long (short) ranged with respect to the lattice constant (correlation-length), yielding the critical exponents as given in the original paper.

cond-mat.stat-mech↗