L. Danaila

A generalization of Yaglom's equation which accounts for the large-scale forcing in heated decaying turbulence

In most real or numerically simulated turbulent flows, the energy dissipated at small scales is equal to that injected at very large scales, which are anisotropic. Despite this injection-scale anisotropy, one generally expects the inertial-range scales to be locally isotropic. For moderate Reynolds numbers, the isotropic relations between second-order and third-order moments for temperature (Yagloms equation) or velocity increments (Kolmogorovs equation) are not respected, reflecting a non-negligible correlation between the scales responsible for the injection, the transfer and the dissipation of energy. In order to shed some light on the influence of the large scales on inertial-range properties, a generalization of Yagloms equation is deduced and tested, in heated grid turbulence ( R λ =66). In this case, the main phenomenon responsible for the non-universal inertial-range behaviour is the non-stationarity of the second-order moments, acting as a negative production term.

Similarity in the far field of a turbulent round jet

In this paper, we test the idea of equilibrium similarity, for which all scales evolve in a similar way in a turbulent round jet, for a prescribed set of initial conditions. Similarity requirements of the mean momentum and turbulent energy equations are reviewed briefly but the main focus is on the velocity structure function equation, which represents an energy budget at any particular scale. For similarity of the structure function equation along the jet axis, it is found that the Taylor microscale λ is the relevant characteristic length scale. Energy structure functions and spectra, measured at a number of locations along the axis of the jet, support this finding reasonably well, i.e., they collapse over a significant range of scales when normalized by λ and the mean turbulent energy ⟨q2⟩. Since the Taylor microscale Reynolds number Rλ is approximately constant (≃450) along the jet axis, the structure functions and spectra also collapse approximately when the normalization uses either the Kolmogorov or...

Similarity of energy structure functions in decaying homogeneous isotropic turbulence

An equilibrium similarity analysis is applied to the transport equation for

Turbulent energy scale budget equations in a fully developed channel flow

\langle(\delta q)^{2}\rangle

Multi-scale energy injection: a new tool to generate intense homogeneous and isotropic turbulence for premixed combustion

(

Turbulent flows and intermittency in laboratory experiments

{\equiv}\,\langle(\delta u)^{2}\rangle + \langle(\delta v)^{2}\rangle + \langle(\delta w)^{2}\rangle

Spectrum of a passive scalar in moderate Reynolds number homogeneous isotropic turbulence

), the turbulent energy structure function, for decaying homogeneous isotropic turbulence. A possible solution requires that the mean energy

Scale-by-scale energy budget on the axis of a turbulent round jet

\langle q^{2}\rangle

Streamwise inhomogeneity of decaying grid turbulence

decays with a power-law behaviour (

Collapse of the turbulent dissipative range on Kolmogorov scales

\langle q^{2}\rangle\,{\sim}\,x^{m}