https://nova.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:36 . Since the Taylor microscale Reynolds number R-lambda is approximately constant (similar or equal to450) along the jet axis, the structure functions and spectra also collapse approximately when the normalization uses either the Kolmogorov or integral length scales. Over the dissipative range, the best collapse occurs when Kolmogorov variables are used. The use of and the integral length scale L provides the best collapse at large separations. A measure of the quality of collapse is given. (C) 2005 American Institute of Physics.]]> Wed 11 Apr 2018 15:49:01 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:31548 χ/d = 10, 20 and 40, where χ is the streamwise distance from the cylinder axis and d is the cylinder diameter, with a Reynolds number of 2.5 x 10³ based on the cylinder diameter and the free-stream velocity. A probe consisting of eight hot wires (four X-wires) and four cold wires is used to measure simultaneously the three components of the fluctuating velocity and vorticity vectors, as well as the fluctuating temperature gradient vector at nominally the same point in the plane of the mean shear. It is found that the enstrophy and scalar dissipation spectra collapse approximately at all wavenumbers except around the Kármán vortex street wavenumber for χ/d ≽ 20. The spectral similarity between the streamwise velocity fluctuation u and the passive scalar θ is better than that between the velocity fluctuation vector q and θ. This is closely related to the highly organized lateral velocity fluctuation v in this flow. The present observations are fully consistent with the expectation that small scales of the velocity and temperature fields are more likely to exhibit a close relationship than scales associated with the bulk of the turbulent energy or scalar variance. The variation across the wake of the time scale ratio between scalar and velocity fields is significantly smaller than that of the turbulent Prandtl number.]]> Sat 24 Mar 2018 08:44:26 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:20918 r on the phase ϕ of the CM. This tool allows the dependence of the RM to be followed as a function of the CM dynamics. Scale-by-scale energy budget equations are established on the basis of phase-averaged structure functions. They reveal that energy transfer at a scale r is sensitive to an additional forcing mechanism due to the CM. Second, these concepts are tested using hot-wire measurements in a cylinder wake, in which the CM is characterized by a well-defined periodicity. Because the interaction between large and small scales is most likely enhanced at moderate/low Reynolds numbers, and is also likely to depend on the amplitude of the CM, we choose to test our findings against experimental data at Rλ∼102 and for downstream distances in the range 10≤x/D≤40. The effects of an increasing Reynolds number are also discussed. It is shown that: (i) a simple analytical expression describes the second-order structure functions of the purely CM. The energy of the CM is not associated with any single scale; instead, its energy is distributed over a range of scales. (ii) Close to the obstacle, the influence of the CM is perceptible even at the smallest scales, the energy of which is enhanced when the coherent strain is maximum. Further downstream from the cylinder, the CM clearly affects the largest scales, but the smallest scales are not likely to depend explicitly on the CM. (iii) The isotropic formulation of the RM energy budget compares favourably with experimental results.]]> Sat 24 Mar 2018 08:06:11 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:27919 J. Fluid Mech., vol. 250, 1993, pp. 651-668) or MA, the new model provides a more detailed description of the role the rib-like structures undertake in transporting heat and momentum, and also underlines the importance of the upstream half of the spanwise vortex rollers, instead of only one quadrant of these rollers, as in the MA model, in diffusing heat out of the vortex.]]> Sat 24 Mar 2018 07:36:07 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:25900 isoalong the centreline in the far-wake of a circular cylinder is derived by applying the limit at small separations to the two-point energy budget equation. It is found that the imbalance between the production and the destruction of ⋶_iso, respectively due to vortex stretching and viscosity, is governed by both the streamwise advection and the lateral turbulent diffusion (the former contributes more to the budget than the latter). This imbalance differs intrinsically from that in other flows, e.g. grid turbulence and the flow along the centreline of a fully developed channel, where either the streamwise advection or the lateral turbulent diffusion of ⋶_iso governs the imbalance. More importantly, the different types of imbalance represent different constraints on the relation between the skewness of the longitudinal velocity derivative S and the destruction coefficient of enstrophy G. This results in a non-universal approach of S towards a constant value as the Taylor microscale Reynolds number R_λ increases. For the present flow, the magnitude of S decreases initially (R_λ≤40) before increasing (R_λ>40) towards this constant value. The constancy of S at large Rλ violates the modified similarity hypothesis introduced by Kolmogorov (J. Fluid Mech., vol. 13, 1962, pp. 82-85) but is consistent with the original similarity hypotheses (Kolmogorov, Dokl. Akad. Nauk SSSR, vol. 30, 1941b, pp. 299-303 (see also 1991 Proc. R. Soc. Lond. A, vol. 434, pp. 9-13)) , and, more importantly, with the almost completely self-preserving nature of the plane far-wake.]]> Sat 24 Mar 2018 07:28:16 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:24300 Sat 24 Mar 2018 07:14:38 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:32998 Exp. Fluids, vol. 53, 2012, pp. 1005–1013) based on the universality of the dissipation range of the longitudinal velocity spectrum normalized by the Kolmogorov scales also applies in the present flow despite the strong perturbation from the Kármán vortex street and violation of local isotropy at small x/d. The appropriateness of the spectral chart method is consistent with Antonia et al.’s (Phys. Fluids, vol. 26, 2014, 45105) observation that the two major assumptions in Kolmogorov’s first similarity hypothesis, i.e. very large Taylor microscale Reynolds number and local isotropy, can be significantly relaxed. The data also indicate that vorticity spectra are more sensitive, when testing the first similarity hypothesis, than velocity spectra. They also reveal that the velocity derivatives δu/δy and δv/δx play an important role in the interaction between large and small scales in the present flow. The phase-averaged data indicate that the energy dissipation is concentrated mostly within the coherent spanwise vortex rollers, in contrast with the model of Hussain (J. Fluid Mech., vol. 173, 1986, pp. 303–356) and Hussain & Hayakawa (J. Fluid Mech., vol. 180, 1987, p. 193), who conjectured that it resides mainly in regions of strong turbulent mixing.]]> Mon 20 Aug 2018 15:42:53 AEST ]]>