Effect of inlet shear on turbulent flow past a wall-mounted finite-size square cylinder

Behera, Sachidananda; Saha, A.

doi:10.1016/j.oceaneng.2021.109270

Cited by 10 publications

(3 citation statements)

References 49 publications

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“…Whether the Re affects the formation of the upwash may also be considered. To verify this possibility, we collected the previous and present results when Re ≥ 500 in figure 24, including those of Wang et al (2006), Wang & Zhou (2009), Bourgeois et al (2011), Kawai et al (2012), Hosseini et al (2013), Uffinger, Ali & Becker (2013), Saeedi et al (2014), Sumner et al (2017), Zhang et al (2017), Unnikrishnan et al (2017), Zu & Lam (2018), Cao et al (2019), da Silva et al (2020, Yauwenas et al (2019), Rastan et al (2021), Behera & Saha (2021) and Zhao et al (2021). The aforementioned data have a range of aspect ratios of H/D = 2.7-18.6.…”

Section: Relationship Between Tip and Near-wake Vorticesmentioning

confidence: 95%

Topological description of near-wall flows around a surface-mounted square cylinder at high Reynolds numbers

et al. 2021

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This study topologically describes near-wall flows around a surface-mounted cylinder at a high Reynolds number ( $Re$ ) of $5\times 10^4$ and in a very thick boundary layer, which were partially measured or technically approximated from the literature. For complete and rational flow construction, we use high-resolution simulations and critical-point theory. The large-scale near-wake vortex is composed of two connected segments rolled up from the sides of the cylinder and from the free end. Another large-scale side vortex clearly roots on two notable foci on the lower side wall. In the junction region, the side vortex moves upwards with a curved trajectory, which induces the formation of nodes on the ground surface. In the free-end region, the side vortex is compressed, which results in a smaller trailing-edge vortex and its downstream movement. Only tip vortices are observed in the far wake. The origin of the tip vortices and their distinction from the near-wake vortex are discussed. Further analyses suggest that $Re$ independence should be treated with high caution when $Re$ increases from 500 to ${O}(10^4)$ . The occurrence of upwash flow behind the cylinder strongly depends on the increase in $Re$ , the mechanism of which is also provided. The separation–reattachment process in the junction region and the trailing-edge vortices are discovered only at a high $Re$ . The former should significantly affect the strength of the side vortex in the junction region and the latter should cause a sharp drop in pressure near the trailing edge.

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Section: Relationship Between Tip and Near-wake Vorticesmentioning

confidence: 95%

Topological description of near-wall flows around a surface-mounted square cylinder at high Reynolds numbers

et al. 2021

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“…They observed that the horseshoe vortices significantly affect the wake flow, particularly when the boundary layer was tripped into turbulent flow. Studies by Castro and Robins (1977); Wang et al (2006); Chen et al (2022); Porteous et al (2019); Behera and Saha (2021) have shown that the incoming boundary layer conditions have a profound effect on the wake behind wall-mounted cylinders.…”

Section: Introductionmentioning

confidence: 99%

Wake Characterization of Building Clusters Immersed in Atmospheric Boundary Layers

Mishra

Placidi

Carpentieri

et al. 2023

Preprint

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Wind tunnel experiments were conducted to understand the effect of building array size (N), aspect ratio (AR), and the spacing between building (WS) on the mean structure and decay of their wakes. Arrays of size 3×3, 4×4,and 5×5, AR = 4, 6, and 8, and WS = 0.5WB, 1WB, 2WB and 4WB (where WB is the building width) were considered. Three different wake regimes behind the clusters were identified: near-, transition-, and far-wake regimes. The results suggest that the spatial extent of these wake regimes is governed by the overall array width (WA). The effects of individual buildings are observed to be dominant in the near-wake regime (0 < x/WA < 0.5) where individual wakes appear behind each building. These wakes are observed to merge together in the ‘transition wake region’ (0.5 < x/WA < 1.5), forming a combined wake in which the individual contributions are no longer apparent. In the far-wake regime (x/WA > 1.5), the wake characteristics and scales of building clusters wakes are similar to those downstream of a single isolated building. Accordingly, new local and global scaling parameters in the near- and far-wake regimes are introduced. The decay of the centreline velocity deficit is then modelled as a function of the three parameters considered in the experiment.

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“…In fluid mechanics, the flow around a square cylinder is a classic problem of flow around a bluff body, which contains complex phenomena such as impact, separation, reattachment, orbiting, and vortex often encountered in various fields ( Lahaye et al, 2014 ; Vikram et al, 2020 ). In addition, many engineering structures and marine cylinder structures involve flow around square cylinders ( Behera and Saha, 2021 ). The study on square cylinders generally focuses on the drag and lift forces and the local instability oscillation caused by the periodic change of both forces.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation and Deep Neural Network Revealed Drag Reduction of Microstructured Three-Dimensional Square Cylinders at High Reynolds Numbers

Wang

2022

Front. Bioeng. Biotechnol.

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Square cylinders are widely used in various fields. For example, they are common structures in fishways. The flow around square cylinders has been a common problem in various fields. However, reducing the flow drag of the square cylinder is a problem that remains unexplored. Many previous studies have reported the drag reduction of 2D square cylinders, which failed to reflect the drag of real structures. Also, some studies focus on the drag force of the inner wall of the square cylinder modified by the microstructure. Achieving drag reduction by microstructuring the surface of the 3D square cylinder is a challenging problem. This study applied a 3D numerical simulation and deep neural network to study the drag reduction performance of the square cylinder under different patch sizes. We studied the drag reduction performance of protrusion and pit-patched square cylinders and tried to find the rule between drag reduction performance and patch configuration. The results show that the square cylinder has better drag reduction performance in some cases. However, its drag reduction performance is greatly affected by the protrusion structure. Also, too large protrusions will increase the drag force of the structure. When the surface protrusion accounts for 10% of the total area of the square cylinder, the drag reduction performance is the best (22.1%). The pit patch structure demonstrated an insignificant drag reduction performance and even increased the drag in most cases. The DNN prediction model demonstrated the robustness of the numerical simulation data.

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Effect of inlet shear on turbulent flow past a wall-mounted finite-size square cylinder

Cited by 10 publications

References 49 publications

Topological description of near-wall flows around a surface-mounted square cylinder at high Reynolds numbers

Topological description of near-wall flows around a surface-mounted square cylinder at high Reynolds numbers

Wake Characterization of Building Clusters Immersed in Atmospheric Boundary Layers

Numerical Simulation and Deep Neural Network Revealed Drag Reduction of Microstructured Three-Dimensional Square Cylinders at High Reynolds Numbers

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