Developing an effective turbulence model is important for engineering applications as well as for fundamental understanding of the flow physics. We present a mathematical derivation of a closure relating the Reynolds stress to the mean strain rate for incompressible flows. A systematic multiscale analysis expresses the Reynolds stress in terms of the solutions of local periodic cell problems. W...

The streamwise and transverse velocities are measured simultaneously in isotropic grid turbulence at relatively high Reynolds numbers Re(lambda) approximately 110-330. Using a conditional averaging technique, we extract typical intermittency patterns that are consistent with velocity profiles of a model for a vortex tube, i.e., Burgers vortex. The radii of the vortex tubes are several of the Ko...

Second and third order longitudinal structure functions and wavenumber spectra of isotropic turbulence are computed using the EDQNM model and compared to results of the multifractal formalism. At the highest Reynolds number available in windtunnel experiments, Rλ = 2500, both the multifractal model and EDQNM give power-law corrections to the inertial range scaling of the velocity increment skew...

A review of recent discoveries from high Reynolds number studies of turbulent boundary layers is given. The emergent regime of very large-scale structures in the logarithmic region and their subsequent influence on the near-wall cycle challenges many of the previously held assumptions regarding scaling of turbulent boundary layers at high Reynolds numbers. Experimental results are presented to ...

We propose a plasma experiment to be used to investigate fundamental properties of astrophysical dynamos. The highly conducting, fast flowing plasma will allow experimenters to explore the high-magnetic-Reynolds-number regime. The plasma is confined using a ring-cusp strategy and subject to a toroidal differentially rotating outer boundary condition. As proof of principle, we present magnetohyd...

Direct numerical simulation of a fully developed turbulent channel flow with passive scalar transport has been carried out at four Reynolds numbers, 180, 395, 640 and 1020, based on the friction velocity and the channel half width. The molecular Prandtl numbers are 0.025 and 0.71 where the working fluids are assumed to be mercury and air, respectively. It is shown that for both Prandtl numbers,...

It is pointed out that, for microscale Reynolds numbers less than about 1000, the passive scalar spectrum in turbulent shear flows is less steep than anticipated and that the Obukhov–Corrsin constant can be defined only if the microscale Reynolds number exceeds this value. In flows where the large-scale velocity field is essentially isotropic ~as in grid turbulence!, the expected 5/3 scaling is...

The analytic expression of the time evolution of the Reynolds stress anisotropy tensor in all planar homogeneous ows is obtained by exact integration of the modeled di erential Reynolds stress equations. The procedure is based on results of tensor representation theory, is applicable for general pressure-strain correlation tensors, and can account for any additional turbulence anisotropy e ects...

cold and earache at the Vatican. If his ears had discharged at the Vatican or afterwards at least one of his biographers, or Reynolds himself in his diary, where he carefully recorded his eye symptoms, would have made some mention of it. Hilles quotes many of Reynolds' letters, in some of which he refers to his poor sight, but never to his poor hearing. Thus it would seem that Sir Joshua Reynol...