Experimental investigation of flow behind a cube for moderate Reynolds numbers

Klotz, Lukasz; Goujon-Durand, S.; Rokicki, Jacek; Wesfreid, José Eduardo

doi:10.1017/jfm.2014.236

Cited by 34 publications

(39 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The experimentally found Strouhal numbers are almost independent of the Reynolds number. Similar results were reported recently by Klotz et al (2014) for a cube placed in a low-Reynolds water tunnel (with cross-section 100 mm × 100 mm, located at PMMH, ESPCI). Unlike the experiments by Calvert, which were carried out in a wind tunnel representing to a large extent an unconfined configuration, our experiments were realized in a water channel with non-negligible blockage factor.…”

Section: Resultssupporting

confidence: 91%

Effect of inclination on the transition scenario in the wake of fixed disks and flat cylinders

et al. 2015

Self Cite

View full text Add to dashboard Cite

International audienceWe take up the old problem of Calvert (J. Fluid Mech., vol. 29, 1967, pp. 691–703) concerning the wake of a cylinder inclined with respect to the flow direction, and consider it from the viewpoint of transition to turbulence. For cylinders placed perpendicular to the flow direction, we address the disagreement between numerical simulation of the ideal axisymmetric configuration and experimental observations. We demonstrate that for a disk (a cylinder of aspect ratio infinity) and a flat cylinder of aspect ratio χ = 6 (ratio of diameter to height), the numerically predicted transition scenario is limited to very small inclination angles and is thus difficult to test experimentally. For inclination angles of about 4 • and more, a joint numerical and experimental study shows that the experimentally observed scenario agrees qualitatively well with the results of numerical simulations. For the flat cylinder χ = 6, we obtain satisfactory agreement with regard to dependence of the critical Reynolds number (Re) of the onset of vortex shedding on the inclination angle. Both for infinitely flat disks and cylinders of aspect ratio χ = 6, a small inclination tends to promote vortex shedding, that is, to lower the instability threshold, whereas for inclination angles exceeding 20 • the opposite effect is exhibited. The Strouhal number of oscillations is found to be only very weakly dependent on the Reynolds number, and very good agreement is obtained between values reported by Calvert (J. Fluid Mech., vol. 29, 1967, pp. 691–703) at high Reynolds numbers and our simulations at Re = 250. In contrast, we observe relatively poor agreement in Strouhal numbers when comparing the results of our numerical simulations and the data acquired from the experimental setup described in this paper. Closer analysis shows that confidence can be placed in the numerical results because the discrepancy can be attributed to the influence of the support system of the flat cylinder. Suggestions for improvement of the experimental setup are provided

show abstract

Section: Resultssupporting

confidence: 91%

Effect of inclination on the transition scenario in the wake of fixed disks and flat cylinders

et al. 2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…4a, b,c,d). We note that the transition to hairpin shedding in JICF in low-velocity-ratio regime is analogous to the transition reported for the wake behind three-dimensional bluff bodies, such as sphere (Johnson & Patel 1999;Gumowski et al 2008), disk (Bobinski et al 2014) and cube (Klotz et al 2014), with similar structure of shed hairpins and with a gentle kinking of two trails of counter-rotating vortices prior to self-sustained shedding of hairpins (see at x/D jet > 8 in Fig. 4c,d).…”

Section: Resultssupporting

confidence: 77%

“…The test section has rectangular cross-section of 15.0 cm width and 10.0 cm height, and length of the channel is 150.0 cm. The crossflow is induced by gravity, using a constant-level tank located above the test section to provide a constant pressure gradient (see also Fig.1 in Klotz et al (2014)). Before entering the test section, the crossflow is conditioned by two honeycomb screens and a 4:1 contraction nozzle.…”

Section: Experimental Set-upmentioning

confidence: 99%

Experiments on a jet in a crossflow in the low-velocity-ratio regime

Klotz

Gumowski²,

Wesfreid

2019

J. Fluid Mech.

Self Cite

View full text Add to dashboard Cite

The hairpin instability of a jet in a crossflow (JICF) for low jet-to-crossflow velocity ratio is investigated experimentally for a velocity ratio range of R ∈ (0.14, 0.75) and crossflow Reynolds numbers Re D ∈ (260, 640). From spectral analysis, we characterize the Strouhal number and amplitude of the hairpin instability as a function of R and Re D . We demonstrate that the dynamics of the hairpins is well described by the Landau model, and hence that the instability occurs through Hopf bifurcation, similarly to other hydrodynamical oscillators such as wake behind different bluff bodies. Using the Landau model, we determine the precise threshold values of hairpin shedding. We also study the spatial dependence of this hydrodynamical instability, which shows a global behaviour.

show abstract

“…The wake and its instabilities behind different 3D static bodies, e.g., sphere, disks, cube, bullets, etc. were considered in the numerical as well as in the experimental studies [1][2][3][4][5][6]. The flow instabilities of a viscous fluid past a rotating sphere may be considered as a simplified case of a more general family of flows around immersed rotating bodies [7,8].…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the wake behind a rotating sphere

et al. 2018

Self Cite

View full text Add to dashboard Cite

The wake behind a sphere, rotating about an axis aligned with the streamwise direction, has been experimentally investigated in a low-velocity water tunnel using LIF visualizations and PIV measurements. The measurements focused on the evolution of the flow regimes that appear depending on two control parameters, namely the Reynolds number Re and the dimensionless rotation or swirl rate Ω, which is the ratio of the maximum azimuthal velocity of the body to the free stream velocity. In the present investigation, we cover the range of Re smaller than 400 and Ω from 0 and 4. Different wakes regimes such as an axisymmetric flow, a low helical state and a high helical mode are represented in the (Re, Ω) parameter plane.

show abstract

Experimental investigation of flow behind a cube for moderate Reynolds numbers

Cited by 34 publications

References 36 publications

Effect of inclination on the transition scenario in the wake of fixed disks and flat cylinders

Effect of inclination on the transition scenario in the wake of fixed disks and flat cylinders

Experiments on a jet in a crossflow in the low-velocity-ratio regime

Experimental investigation of the wake behind a rotating sphere

Contact Info

Product

Resources

About