LES of the flow around two cylinders in tandem

Palau-Salvador, Guillermo; Stoesser, Thorsten; Rodi, W.

doi:10.1016/j.jfluidstructs.2008.07.002

Cited by 56 publications

(31 citation statements)

References 20 publications

(26 reference statements)

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“…Finally, the results for the single finite-height cylinder provide important basic information and guidance for attempts to calculate the even more complex, in practice also very important situations of tandem or groups of cylinders where the flow around the individual cylinders interacts. In this vein, the knowledge gathered from the singlecylinder simulations has already been applied in such calculations as reported in Palau et al [39] and Stoesser et al [40].…”

Section: Discussionmentioning

confidence: 99%

Large Eddy Simulations and Experiments of Flow Around Finite-Height Cylinders

Palau-Salvador

Stoesser

Fröhlich

et al. 2009

Flow Turbulence Combust

115

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The paper presents experimental and numerical results for the flow around a surface-mounted circular cylinder at the two height-to-diameter ratios of 2.5 and 5. The Reynolds number based on approach flow velocity and cylinder diameter is 43,000 and 22,000 for these two cases and the boundary layer of the approach flow has a thickness of about 10% of the cylinder height. The experiments comprise both flow visualizations with dye and laser Doppler velocimeter measurements of all mean velocity and fluctuation components. The numerical study is performed by an elaborate large eddy simulation on a staggered Cartesian grid using the immersed boundary method. The instantaneous flow behaviour including the shedding is analysed with information based on animations. For the long cylinder alternating shedding is found to occur over most of the height while for the shorter cylinder the shedding is observed mainly near the ground where it is also mostly alternating but intermittently also symmetrical. The mean-flow behaviour is analysed with the aid of streamlines and contour plots of mean-velocity and fluctuation components Flow Turbulence Combust (2010) 84:239-275 in various planes and a detailed comparison of LES and LDV results is provided, showing generally good agreement. The LES with very fine resolution near the free end allow a detailed study of the complex flow in this region with owl-face topology on the end wall previously observed in experiments. Behind the cylinder, the longitudinal recirculation region, the downstream development of tip vortices and the emergence of trailing vortices further downstream are analysed. The sum of the results, together with those from previous studies that were reviewed extensively, provides a comprehensive picture of the very complex flow behaviour.

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Section: Discussionmentioning

confidence: 99%

Large Eddy Simulations and Experiments of Flow Around Finite-Height Cylinders

Palau-Salvador

Stoesser

Fröhlich

et al. 2009

Flow Turbulence Combust

115

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“…In lateral direction a domain width of 8D was chosen. These values were selected based on previous LES in the group of the last author [11,[21][22][23] of flow past cylinders. As will be described later, at the lateral boundaries a periodic condition was applied so that strictly the flow situation considered is that of a matrix of tandem cylinders with sideways distance of 8D between the cylinder pairs.…”

Section: Configuration Investigatedmentioning

confidence: 99%

“…This situation with flow over the top of the cylinders is even more complex than that between passage walls. In the group of the last author, LES calculations were carried out for a similar situation [23], namely for tandem cylinders submerged in an open channel as measured by Kadota et al (unpublished). Closest to the study of flow past tandem cylinders in a passage are the recent experiments of Ataie-Ashtiani and Aslani-Kordkandi [2].…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulation of Flow Past Tandem Cylinders in a Channel

AlQadi

Alhazmy

Al-Bahi

et al. 2015

Flow Turbulence Combust

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The paper presents Large Eddy Simulation (LES) of flow around two circular cylinders in tandem placed in an open channel. This and the closely related situation of tandem cylinders in a passage are rich of complex flow phenomena and of considerable practical and fundamental interest. The configuration was set up to correspond closely to an experiment (Ataie-Ashtiani and Aslani-Kordkandi Flow Turbul. Combust. 90(3), 471-490 (2013)) with detailed velocity measurements. The ratio of the distance between the cylinders, L, and the cylinder diameter, D, and the ratio of water depth h to D, are L/D = 3 and h/D = 3.1, respectively, as in the experiment. However, a lower Reynolds number had to be used and a smooth channel wall instead of a somewhat rough wall in the experiments. The Reynolds numbers based on channel height and cylinder diameter are 22,600 and 7,300 respectively. A fine grid was employed so that the LES is well resolved and the results are little affected by the subgrid-scale model (dynamic Smagorinsky) and represent well the actual physical processes of the situation studied. A comparison with experimental results of mean flow, turbulence quantities and shedding frequency shows that there is good agreement about all the main features, but there are some quantitative differences as the flow situations differed in some respects. The complex 3D flow behaviour is analyzed and described with the aid of the LES results, and these also provide benchmark data for testing other, less costly calculation methods which are preferred in practice.

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“…2-4). However, fewer studies have examined the impact of the flow structure in the near-wake region when the obstruction is completely submerged with the flow overtopping the tip of the obstruction, 1,5,6 a condition relevant to river engineering, coastal engineering, and wind engineering. For such emergent flows, the wake characteristics and flow patterns are dependent on the aspect ratio and Reynolds number.…”

Section: Introductionmentioning

confidence: 99%

“…24 The flow around submerged bluff bodies is largely dominated by energetic flow structures and significant flow separation which constitutes a challenge for numerical modeling. LES has been widely used to study submerged cylinders 1,25 due to its ability to resolve complex phenomena such as energetic large-scale structures, flow separation at the top of the upstream face, 6,19 or tip vortices. 10 With the exception of the aforementioned studies, there is a scarcity of experimental and numerical studies examining the wakes of submerged obstacles in shallow flows despite their importance in hydraulic and geophysical contexts.…”

Section: Introductionmentioning

confidence: 99%

Large-eddy simulation of shallow turbulent wakes behind a conical island

et al. 2017

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Large-Eddy Simulations (LESs) and experiments were employed to study the influence of water depth on the hydrodynamics in the wake of a conical island for emergent, shallow, and deeply submerged conditions. The Reynolds numbers based on the island’s base diameter for these conditions range from 6500 to 8125. LES results from the two shallower conditions were validated against experimental measurements from an open channel flume and captured the characteristic flow structures around the cone, including the attached recirculation region, vortex shedding, and separated shear layers. The wake was impacted by the transition from emergent to shallow submerged flow conditions with more subtle changes in time-averaged velocity and instantaneous flow structures when the submergence increases further. Despite differences in the breakdown of the separated shear layers, vortex shedding, and the upward flow region on the leeward face (once the cone’s apex is submerged), similar flow structures to cylinder flow were observed. These include an arch vortex tilted in the downstream direction and von Karman vortices in the far-wake. Spectra of velocity time series and the drag coefficient indicated that the vortex shedding was constrained by the overtopping flow layer, and thus the shedding frequency decreased as the cone’s apex became submerged. Finally, the generalised flow structures in the wake of a submerged conical body are outlined.

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LES of the flow around two cylinders in tandem

Cited by 56 publications

References 20 publications

Large Eddy Simulations and Experiments of Flow Around Finite-Height Cylinders

Large Eddy Simulations and Experiments of Flow Around Finite-Height Cylinders

Large Eddy Simulation of Flow Past Tandem Cylinders in a Channel

Large-eddy simulation of shallow turbulent wakes behind a conical island

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