https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:43679 Wed 28 Sep 2022 14:37:38 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:39590 Wed 15 Jun 2022 12:47:21 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:37688 L) and jet impingement angle on the flow characteristics of an obliquely inclined submerged water jet. Measurements were taken for L=1D, 2D, 4D and 6D (where D is the diameter of the nozzle) for the jet impingement angle (θ) of 45° and 26°, and the flow characteristics in the uphill and the downhill regions are investigated at Reynolds number of 2600 (based on the nozzle diameter D and the jet velocity U_o). It is observed that surface spacing has an opposite effect in the uphill and the downhill regions in terms of wall jet flow. In the uphill region, the tendency of the wall jet to grow increases with increase in L/D. However, in the downhill region, the jet velocity and its thickness are observed to reduce as the separation distance is increased. The distance between the stagnation point and the geometric centre is observed to decrease with increase in L/D because of jet–ambient fluid interaction in the uphill region. The jet width is observed to grow for θ=45^o in the downstream of the plate due to enhanced jet–ambient fluid interaction. Flow at θ=26° shows that after impingement the entire jet deviates towards the downhill side, which indicates the existence of a critical impingement angle below which there is no flow of the jet in the uphill region. RMS velocity fluctuations and shear stress show an increased turbulence level downstream of the plate in the downhill region for smaller impinging distance implying higher jet–ambient fluid interaction and increased jet width. They, along with the negative turbulence production term, reveal the region of flow separation and reattachment. The decrease in the peak value of Nusselt number can be related to the drop in the jet momentum at the stagnation point with increase in the surface spacing.]]> Tue 16 Mar 2021 10:51:58 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:36610 ∈, on the distance from the wall and the Taylor microscale Reynolds number, Re_λ. The locally isotropic expression <∈_iso> is used as a surrogate for the mean turbulent kinetic energy dissipation rate, <∈>, for calculating [formula could not be replicated] are the integral length scale and the rms of the longitudinal velocity fluctuation, respectively. The measurements show that C_∈ varies significantly near the wall, but becomes almost constant in the region 0.2≤y/δ≤0.6 of the boundary layer, a region where Re_λ is also practically constant.]]> Tue 16 Jun 2020 10:44:42 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:467 Thu 25 Jul 2013 09:09:54 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:488 Thu 25 Jul 2013 09:09:52 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:40307 Thu 07 Jul 2022 16:28:37 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:9303 Sat 24 Mar 2018 08:41:19 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:9404 Sat 24 Mar 2018 08:39:33 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:9626 Sat 24 Mar 2018 08:35:24 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:12474 m dependence of the KH instability frequency (f _KH) with different values of m over different ranges of Re, as reported previously in the literature. However, it is found that this power-law dependence is not exact, and a third-order polynomial dependence appears to fit the data well over the full range of Re. Importantly, it is found that the wake shear-layer instabilities can be grouped into three categories: (1) one with frequencies much smaller than the Bénard–Kármán-vortex shedding frequency, (2) one associated with the vortex shedding and (3) one related to the KH instability. The low-frequency shear-layer instabilities from both sides of the cylinder are in-phase, in contrast to the anti-phase high-frequency KH instabilities. Finally, the observed streamwise decrease in the mean KH frequency provides strong support for the occurrence of vortex pairing in wake shear layers from a circular cylinder, thus implying that both the wake shear layer and a mixing layer develop in similar fashion.]]> Sat 24 Mar 2018 08:16:30 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:21391 λ is sufficiently large. The method is in fact applied to the lower wavenumber end of the dissipative range thus avoiding most of the problems due to inadequate spatial resolution of the velocity sensors and noise associated with the higher wavenumber end of this range.The use of spectral data (30 ≤ R_λ ≤ 400) in both passive and active grid turbulence, a turbulent mixing layer and the turbulent wake of a circular cylinder indicates that the method is robust and should lead to reliable estimates of ⟨ε⟩ in flows or flow regions where the first similarity hypothesis should hold; this would exclude, for example, the region near a wall.]]> Sat 24 Mar 2018 08:05:03 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:19671 Sat 24 Mar 2018 08:01:13 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:5137 0.2. Similar results were also observed for second-order structure functions (not shown) for Kolmogorov normalised radius r* < 10. Although, the quality of collapsed is poorer for transverse component, the result highlights that Kolmogorov similarity hypothesis is reasonably well satisfied. However, the suction results shows a significant departure from the no suction case of the Kolmogorov normalised spectra and second-order structure functions for k₁* < 0.2 and r* > 20, respectively. The departure at the larger scales with collapse at the small scales suggests that suction induce a change in the small-scale motion. This is also reflected in the alteration of mean turbulent energy dissipation rate and Taylor microscale Reynolds number. This change is a result of the weakening of the large-scale structures. The effect is increased as the suction rate is increased.]]> Sat 24 Mar 2018 07:49:39 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:326 Sat 24 Mar 2018 07:42:41 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:64 Sat 24 Mar 2018 07:42:03 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:30242 n is a positive integer). It is found that the relation M_2n+1(∂u/∂z)∼R⁻¹_λ is supported reasonably well by hot-wire data up to the seventh order (n=3) on the wake centreline, although it is also dependent on the initial conditions. The present relation N3(∂u/∂y)∼R⁻¹_λ is obtained more rigorously than that proposed by Lumley (Phys Fluids 10:855–858, 1967) via dimensional arguments. The effect of the mean shear at locations away from the wake centreline on M_2n+1(∂u/∂z) and N_2n+1(∂u/∂y) is addressed and reveals that, although the non-dimensional shear parameter is much smaller in wakes than in a homogeneous shear flow, it has a significant effect on the evolution of N_2n+1(∂u/∂y) in the direction of the mean shear; its effect on M_2n+1(∂u/∂z) (in the non-shear direction) is negligible.]]> Sat 24 Mar 2018 07:41:58 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:27364 Sat 24 Mar 2018 07:36:42 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28197 τ and the error in the origin, d₀, which are the two prominent issues that surround rough-wall boundary layers. In addition, velocity measurements are taken at several streamwise locations using hot-wire anemometry to obtain C_f from the momentum integral equation. Results showed that both methods give consistent values for U_τ, indicating that the contribution of the viscous drag over this rough wall is negligible. This supports the results of Perry et al. (J Fluid Mech 177:437–466, 1969) and Antonia and Luxton (J Fluid Mech 48(04):721–761, 1971) in a boundary layer and of Leonardi et al. (2003) in a channel flow but does not agree with those of Furuya et al. (J Fluids Eng 98(4):635–643, 1976). The results show that both U_τ and d₀ can be unambiguously measured on this particular rough wall. This paves the way for a proper comparison between the boundary layer developing over this wall and the smooth-wall turbulent boundary layer.]]> Sat 24 Mar 2018 07:23:52 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:4722 Sat 24 Mar 2018 07:21:50 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:4754 Sat 24 Mar 2018 07:21:07 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:22594 Sat 24 Mar 2018 07:15:59 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:47776 Mon 30 Jan 2023 09:49:09 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:18658 Mon 20 Jul 2015 17:06:12 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:41306 Mon 01 Aug 2022 12:23:31 AEST ]]>