Direct numerical simulation of turbulent wake behind a surface-mounted square cylinder

Saeedi, Mohammad; LePoudre, Philip P.; Wang, Bing-Chen

doi:10.1016/j.jfluidstructs.2014.06.021

Cited by 53 publications

(37 citation statements)

References 36 publications

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“…This value is relatively larger than its counterpart in the 2D scenario in view of that Re cri-2D = 30-60 (Breuer et al 10 ), Re cri-2D < 70 (Okajima 53 ), and Re cri-2D = 54 (Klekar and Patankar 54 ). The value of S t falls in S t = [0.100, 0.123], being in accordance with the numerical results of Wang and Zhou 1 (AR = 7, Re = 9300, and St = 0.110), Saeedi et al 12 (AR = 4, Re = 12 000, and St = 0.106), and Bourgeois et al 3,45 (AR = 4, Re = 12 000, and St = 0.100 ± 0.003). When it comes to the types of mean streamwise vortices and the spanwise vortexshedding model (serving as the two main innovations of this paper), various kinds of vortex structures exist in the range of the Re considered in this study, which will be detailed in Sec.…”

Section: Validation and Grid Convergencesupporting

confidence: 89%

“…The reasons will be given in the following. The transverse instantaneous tip vortex has been observed by Saeedi et al 12 and Hwang and Yang; 18 however, no such kind of vortex-shedding is observed in this study, which may be attributed to the much lower Re values considered here. The streamwise instantaneous tip vortices are identified by investigating the vorticity field, being consistent with the observations of Roh and Park, 38 Hain et al, 40 Krajnovic, 5 and Park and Lee, 17,39 but, this type of vortex quickly vanishes along the streamwise direction (being visible only when X/D ≈ 1-3 in Figs.…”

Section: Physical Model Of Vortex-sheddingcontrasting

confidence: 63%

“…For example, Kawamura et al 4 (AR = 1-8, Re = 3.2 × 10 4 ), Park and Lee 17,39 (AR = 6-13, Re = 2 × 10 4 ), Krajnovic 5 (AR = 6, Re = 2 × 10 4 ), Pattenden et al 33 (AR = 1, Re = 2 × 10 5 ), Hain et al 40 (AR ≈ 2.17, Re = 1 × 10 5 ), Leder 41 (AR = 2, Re = 2 × 10 5 ), and Johnston and Wilson 42 found only one pair of "streamwise instantaneous tip vortices" near the free end. Transverse instantaneous tip vortex (being different from the streamwise tip vortex), caused by the vortex-shedding from the leading edge of the free end, has been observed by Saeedi et al 12 (AR = 4, Re = 1.2 × 10 4 ) and Hwang and Yang 18 (AR = 1, Re = 3500). Additionally, Sumner and Heseltine 2 and Sumner et al 21 studied the time-averaged streamwise vortices in the wake of a finite circular cylinder (AR = 3-9, Re = 6 × 10 4 , δ/D = 2.6), and their research showed that either a dipole type or a quadrupole type appears depending on the aspect ratio (AR) value.…”

Section: Introductionmentioning

confidence: 92%

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Direct numerical simulation of flow around a surface-mounted finite square cylinder at low Reynolds numbers

Zhang

Cheng

et al. 2017

Physics of Fluids

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With the aid of direct numerical simulation, this paper presents a detailed investigation on the flow around a finite square cylinder at a fixed aspect ratio (AR) of 4 and six Reynolds numbers (Re = 50, 100, 150, 250, 500, and 1000). It is found that the mean streamwise vortex structure is also affected by Re, apart from the AR value. Three types of mean streamwise vortices have been identified and analyzed in detail, namely, “Quadrupole Type” at Re = 50 and Re = 100, “Six-Vortices Type” at Re = 150 and Re = 250, and “Dipole Type” at Re = 500 and Re = 1000. It is the first time that the “Six-Vortices Type” mean streamwise vortices are reported, which is considered as a transitional structure between the other two types. Besides, three kinds of spanwise vortex-shedding models have been observed in this study, namely, “Hairpin Vortex Model” at Re = 150, “C and Reverse-C and Hairpin Vortex Model (Symmetric Shedding)” at Re = 250, and “C and Reverse-C and Hairpin Vortex Model (Symmetric/Antisymmetric Shedding)” at Re = 500 and Re = 1000. The newly proposed “C and Reverse-C and Hairpin Vortex Model” shares some similarities with “Wang’s Model” [H. F. Wang and Y. Zhou, “The finite-length square cylinder near wake,” J. Fluid Mech. 638, 453–490 (2009)] but differs in aspects such as the absence of the connection line near the free-end and the “C-Shape” vortex structure in the early stage of the formation of the spanwise vortex.

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Section: Validation and Grid Convergencesupporting

confidence: 89%

Section: Physical Model Of Vortex-sheddingcontrasting

confidence: 63%

Section: Introductionmentioning

confidence: 92%

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Direct numerical simulation of flow around a surface-mounted finite square cylinder at low Reynolds numbers

Zhang

Cheng

et al. 2017

Physics of Fluids

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“…The CFDSC 2012 Challenge aimed at evaluating the respective merits and stages of development of the different computational techniques: direct numerical simulation (DNS), large eddy simulation (LES) and Reynolds averaged Navier Stokes (RANS) models. This study is an extension of our DNS analysis presented in the Challenge by Malm et al [10] Some other relevant contributions were the assessment of vortical structures in the wake with LES by Shademan et al, [11] the evaluation of the impact of the incoming boundary layer state carried out with LES by Chen et al [12] and the compilation of turbulent statistics performed with DNS by Saeedi et al [13] The most widely used approach in industry is RANS due to its relative simplicity and reduced computational cost, although some standard RANS models are known to fail when computing geometries relatively different from the ones for which they were calibrated. [14] For instance, Wilcox [15] showed that the commonly used two-equation k − ε model originally proposed by Launder and Spalding [16] performed well under ZPG TBL configurations, but failed when predicting boundary layers subjected to adverse pressure gradients.…”

Section: Introductionmentioning

confidence: 99%

Direct numerical simulation of the flow around a wall-mounted square cylinder under various inflow conditions

Vinuesa

Schlatter

Malm

et al. 2015

Journal of Turbulence

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The flow around a wall-mounted square cylinder of side d is investigated by means of direct numerical simulation (DNS). The effect of inflow conditions is assessed by considering two different cases with matching momentum-thickness Reynolds numbers Re θ 1000 at the obstacle: the first case is a fullyturbulent zero pressure gradient boundary layer, and the second one is a laminar boundary layer with prescribed Blasius inflow profile further upstream. An auxiliary simulation carried out with the pseudo-spectral Fourier-Chebyshev code SIMSON is used to obtain the turbulent time-dependent inflow conditions which are then fed into the main simulation where the actual flow around the cylinder is computed. This main simulation is performed, for both laminar and turbulent-inflows, with the spectral-element method code Nek5000. In both cases the wake is completely turbulent, and we find the same Strouhal number St 0.1, although the two wakes exhibit structural differences for x > 3d downstream of the cylinder. Transition to turbulence is observed in the laminar-inflow case, induced by the recirculation bubble produced upstream of the obstacle, and in the turbulent-inflow simulation the streamwise fluctuations modulate the horseshoe vortex. The wake obtained in our laminar-inflow case is in closer agreement with reference particle image velocimetry measurements of the same geometry, revealing that the experimental boundary layer was not fully turbulent in that dataset, and highlighting the usefulness of DNS to assess the quality of experimental inflow conditions.

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“…A "tall cube" with aspect ratio 4 was simulated been by Saedi et.al. [60] at Re b = 12K where b indicates the base width. The building-like obstacle was subjected to an incident turbulent boundary layer of δ 99 = 0.18h.…”

Section: Introductionmentioning

confidence: 99%

Direct Numerical Simulation of Flow Over a Wall-Mounted Cube with the Nek5000 Spectral Element Code: DNS at <em>Re<sub>h</sub></em> = 3900

Haering

Balakrishnan

Kotamarthi

2021

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The direct numerical simulation (DNS) of the canonical wall-mounted unit cube subjected to two distinct incident velocity profiles is performed at a Reynolds number where the bulk flow characteristics are known to become relatively Reynolds number insensitive. The aim of this work is to highlight the sensitivity of such bluff-body flows to mean shear and to provide a representative set of data for such flow scenarios where common turbulence modeling techniques often fail. Simple boundary conditions and a small domain are selected to allow for cost-effective and easy comparisons for model development purposes. In addition to mean velocity profiles, select turbulence statistics are presented in detail. Further, the basic efficacy of eddy viscosity models is evaluated and found to be adequate only for the shear stress components for the bluff-body flows examined here. Other failure mechanisms for RANS are proposed.

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Direct numerical simulation of turbulent wake behind a surface-mounted square cylinder

Cited by 53 publications

References 36 publications

Direct numerical simulation of flow around a surface-mounted finite square cylinder at low Reynolds numbers

Direct numerical simulation of flow around a surface-mounted finite square cylinder at low Reynolds numbers

Direct numerical simulation of the flow around a wall-mounted square cylinder under various inflow conditions

Direct Numerical Simulation of Flow Over a Wall-Mounted Cube with the Nek5000 Spectral Element Code: DNS at <em>Re<sub>h</sub></em> = 3900

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