Influence of aspect ratio on the mean flow field of a surface-mounted finite-height square prism

Sumner, D.; Rostamy, Noorallah; Bergstrom, Donald J.; Bugg, J. D.

doi:10.1016/j.ijheatfluidflow.2017.02.004

Cited by 67 publications

(37 citation statements)

References 41 publications

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“…The prism aspect ratio is another geometrical parameter that has substantial effect on the wake dynamics [15,16]. Using DNS, Saha (2013) [15] illustrated that the strength of tip downwash flow, drag coefficient, Strouhal number, and wake flow unsteadiness of a short-depth (vertically oriented) cylinder increases with increasing aspect ratio at Re = 250.…”

Section: Introductionmentioning

confidence: 99%

“…Using DNS, Saha (2013) [15] illustrated that the strength of tip downwash flow, drag coefficient, Strouhal number, and wake flow unsteadiness of a short-depth (vertically oriented) cylinder increases with increasing aspect ratio at Re = 250. Later experimental studies of Sumner et al (2017) [16] focused on a higher Reynolds number of 4.2 × 10 4 , which identified the presence of a critical aspect-ratio, after which the wake regime is altered. However, these studies focused on high Re and small depth-ratios.…”

Section: Introductionmentioning

confidence: 99%

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The Steady Wake of a Wall-Mounted Rectangular Prism with a Large-Depth-Ratio at Low Reynolds Numbers

2021

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The wakes of wall-mounted small (square) and large (long) depth-ratio rectangular prisms are numerically studied at Reynolds numbers of 50–250. The large depth-ratio significantly alters the dominance of lateral secondary flow (upwash and downwash) in the wake due to the reattachment of leading-edge separated flow on the surfaces of the prism. This changes the wake topology by varying the entrained flow in the wake region and changing the distribution of vorticity. Thus, the magnitude of vorticity significantly decreases by increasing the prism depth-ratio. Furthermore, the length of the recirculation region and the orientation of near wake flow structures are altered for the larger depth-ratio prism compared to the square prism. Drag and lift coefficients are also affected due to the change of pressure distributions on the rear face of the prism and surface friction force. This behavior is consistently observed for the entire range of Reynolds numbers considered here. The wake size is scaled with Re1/2, whereas drag coefficient scaled with Re−0.3.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Steady Wake of a Wall-Mounted Rectangular Prism with a Large-Depth-Ratio at Low Reynolds Numbers

2021

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“…Bluff body aeroacoustics analyses performed on the cylinders, square prisms, and turret studies indicate that the change in aspect ratio (AR = h/D) tends to change the lateral vortex size resulting in changes in unsteady pressure foot-print on the mounting surface away from the body and reduced the far-field noise by up to 10 dB. [41][42][43] Similarly, the HRM, which has been extensively studied as a benchmark case, can suitably be modified over a real vehicle or a mounting plate arrangement to closely mimic realistic inclinations or aspect ratios to better understand the change in noise generation that is induced by topological changes. Therefore, in this study, we present two changes to the generic side-view mirror viz., Aspect Ratio (AR)…”

Section: B Scope Of Workmentioning

confidence: 99%

Noise emitted from a generic side-view mirror with different aspect ratios and inclinations

2021

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Noise radiated from flow past different configurations of the Half-Round Mirror (HRM) mounted on a plate has been investigated using computational aeroacoustics (CAA).The Stress-Blended Eddy Simulation (SBES), together with the Ffowcs Williams-Hawkings (FW-H) acoustic analogy, was employed to predict near field flow and far-field noise, respectively. The numerical methodology was verified and validated for the standard HRM case against several previously published numerical and experimental data sets, which provides good agreement. Further, (i) the choice of different type of grids for CAA and (ii) the applicability of methods such as the Kirchhoff integral and the FW-H using near field inputs computed from the SBES were assessed. As a next step, the effect of induced noise from the HRM for different a) Aspect Ratios (AR) ranging from 1 to 2.5 and b) inclination of the mirror towards the plate (θ) ranging from 0° to 32° were investigated. For all the investigated cases, the distribution of the radiated noise exhibits a dipole-like structure closer to the plate and a monopole-like structure away from the plate. By inclining the mirror closer to the mounting plate, the emitted noise is reduced both in the vertical and lateral directions of the wake, whereas an increase in the AR of the mirror increases the induced noise considerably. The findings from the current study can provide a deeper understanding for effectively mitigating the induced aerodynamic noise from side-view mirrors.

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“…Moreover, the effect of roughness and time constant of the exponential heat supply on the transient critical heat flux (CHF), maximum heat transfer coefficient (HTC) and onset of nucleate boiling (ONB) was extensively investigated as well. In addition, Sumner et al assessed the effects of the aspect ratio and incidence angle on the flow structure above the free ends of a surface-mounted finite-height circular cylinder and a finite-height square prism [28,29]. Regarding Shinde et al [30], they performed a large eddy simulation of a flow over a wall-mounted cube-shaped obstacle placed in a spatially evolving boundary layer for the purpose of understanding how variations in the cube height can modify the flow dynamics in the case where the cube is inside the boundary layer.…”

Section: Introductionmentioning

confidence: 99%

Turbulent Flow Around Obstacles: Simulation and Study with Variable Roughness

Yousfi¹,

Aliane²

2021

IJHT

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The present work aims to investigate the recirculation and incipient mixing zones in a channel flow supplied with obstacles. The main objective is to develop a new technique to control these recirculation zones by setting a variable roughness. For the purpose of varying that roughness, 4 small bars of heights 0.25H, 0.5H, 0.75H and H were placed downstream of the obstacle; H is the height of the obstacle. For this, a three-dimensional numerical approach was carried out using the ANSYS CFX computer code. In addition, the governing equations were solved using the finite volume method. The K-ω shear-stress transport (SST) turbulence model was utilized to model the turbulent stresses. In the end, we presented the time-averaged simulation results of the contours of the current lines (3D time-averaged streamlines, trace-lines), three components of the velocities: <u> (velocity u contour), <v> (velocity v contour) and <w> (velocity w contour), trace-lines, stream ribbons and mean Q-criterion iso-surface.

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Influence of aspect ratio on the mean flow field of a surface-mounted finite-height square prism

Cited by 67 publications

References 41 publications

The Steady Wake of a Wall-Mounted Rectangular Prism with a Large-Depth-Ratio at Low Reynolds Numbers

The Steady Wake of a Wall-Mounted Rectangular Prism with a Large-Depth-Ratio at Low Reynolds Numbers

Noise emitted from a generic side-view mirror with different aspect ratios and inclinations

Turbulent Flow Around Obstacles: Simulation and Study with Variable Roughness

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