Investigation of wall pressures and surface flow patterns on a wall-mounted square cylinder using very high-resolution Cartesian mesh

Cao, Yong; Tamura, Tetsuro; Kawai, Hidenori

doi:10.1016/j.jweia.2019.02.013

Cited by 44 publications

(20 citation statements)

References 25 publications

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“…The duration of the statistical average is approximately 200t * , which corresponds to approximately 20 periods of Kármán vortex shedding. The temporal convergence of statistical pressures, forces and velocity is examined in Appendix B and by Cao et al (2019). The computations were performed on a K-computer, one of the highest calibre supercomputers known.…”

Section: Methodsmentioning

confidence: 99%

“…On the side wall, a (partially) quasi-horizontal dividing line could be identified, above and below which the mean streamlines turned upwards/downwards (Rastan et al 2017;Zhang et al 2017), although the dividing line passed through the lower corner at the highest Re (i.e. 1000) tested by Zhang et al (2017) Considering the lack of near-wall flow patterns, particularly for high-Re flows, our previous work (Cao, Tamura & Kawai 2019) offers a database of near-wall flows visualised by skin-friction lines on the walls based on very high-resolution numerical simulations when Re was 5 × 10 4 . The visualisation indicated a noticeable difference in the near-wall flow pattern between the low-and high-Re flows.…”

Section: Near-wall Flow Patternsmentioning

confidence: 95%

“…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: 98%

“…The border between two neighbouring regions corresponds to two notable saddle points in the surface flow pattern of the side wall. Following the classification of Cao et al (2019), the 3-D flow separation is topologically described separately in terms of the junction influence region (in § 5) and free-end influence region (in § 6).…”

Section: Flow Separation In the Junction Influence Regionmentioning

confidence: 99%

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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: Methodsmentioning

confidence: 99%

Section: Near-wall Flow Patternsmentioning

confidence: 95%

Section: Relationship Between Tip and Near-wake Vorticesmentioning

confidence: 98%

Section: Flow Separation In the Junction Influence Regionmentioning

confidence: 99%

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

et al. 2021

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“…This simple improvement yields critical benefits that will not cause errors in any types of geometry data, and is applicable to Cartesian grids. We have applied the variations of these methods to various industrial problems [8,13,9,3,4,11]. For COVID-19 digital twins of societal situations, the optimal method was selected for one making it possible to automatically and robustly simulate complex dirty geometry, reducing the time required for preprocessing to about 10 minutes or less.…”

Section: Rapid Mesh Generation Based On the Immersed Boundary Methodsmentioning

confidence: 99%

Digital transformation of droplet/aerosol infection risk assessment realized on "Fugaku" for the fight against COVID-19

Ando¹,

Bale²,

Li³

et al. 2021

Preprint

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The fastest supercomputer in 2020, Fugaku, has not only achieved digital transformation of epidemiology in allowing end-to-end, detailed quantitative modeling of COVID-19 transmissions for the first time, but also transformed the behavior of the entire Japanese public through its detailed analysis of transmission risks in multitudes of societal situations entailing heavy risks. A novel aerosol simulation methodology was synthesized out of a combination of a new CFD methods meeting industrial demands, CUBE [8], which not only allowed the simulations to scale massively with high resolution required for micrometer virus-containing aerosol particles, but also extremely rapid time-to-solution due to its ability to generate the digital twins representing multitudes of societal situations in minutes not week, attaining true overall application high performance; such simulations have been running for the past 1.5 years on Fugaku, cumulatively consuming top supercomputer-class resources and the result communicated by the media as well as becoming official public policies. Keywords COVID-19 • Computational fluid dynamics • Building cube method • Immersed boundary method • Dirty CAD • Droplet/Aerosol transmission • societal behavioral change * All authors are listed in alphabetical order by surnames.

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CFD simulations of wind flow and mean surface pressure for buildings with balconies: Comparison of RANS and LES

Zheng

Montazeri

Blocken

2020

Building and Environment

123

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Investigation of wall pressures and surface flow patterns on a wall-mounted square cylinder using very high-resolution Cartesian mesh

Cited by 44 publications

References 25 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

Digital transformation of droplet/aerosol infection risk assessment realized on "Fugaku" for the fight against COVID-19

CFD simulations of wind flow and mean surface pressure for buildings with balconies: Comparison of RANS and LES

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