Development of a new Lagrangian vortex method for evaluating effects of surfaces roughness

Bimbato, Alex Mendonça; Pereira, Luiz Antonio Alcântara; Hirata, Miguel Hiroo

doi:10.1016/j.euromechflu.2018.09.001

Cited by 13 publications

(61 citation statements)

References 31 publications

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“…The present numerical results can be useful for a future comparison with a more detailed three-dimensional study, being the starting point for future, more elaborated experimental investigations. The LES modeling used in this work was validated in earlier studies by Bimbato et al [7,8]. This kind of flow is of direct relevance to many practical applications (e.g., tall buildings, trains, bridge piers, chimneys, periscopes, heat transfer tubes, cables, wires, and so on).…”

Section: Introductionmentioning

confidence: 82%

“…In the second one, the surface roughness effect is analyzed. A mean surface roughness height of ε * /d * = 0.007 was chosen for the tests, because it introduces greater instabilities in the boundary layer of cylinder [8]. This order of surface roughness height is typical for support columns of large offshore floating structures after a good pair of years operating under several environmental conditions.…”

Section: Methodsmentioning

confidence: 99%

“…The average speed differences, necessary to (1) Re = U * d * compute the second-order velocity structure function of the filtered field, are considered for each rough point. Bimbato et al [8] proposed the following adaptation for the secondorder velocity structure function model of the filtered field [28]:…”

Section: Methodsmentioning

confidence: 99%

“…In a recent paper, Bimbato et al [8] presented numerical results of the flow around a circular cylinder in a subcritical flow regime of Reynolds number Re = 1.0 × 10 5 using a Lagrangian vortex method with two-dimensional modeling of roughness. Subcritical flow by definition is the condition at which the boundary layer over the cylinder remains laminar and the transition takes place at some points after separation.…”

Section: Introductionmentioning

confidence: 99%

“…The goal of this paper is to apply the methodology developed by Bimbato et al [6][7][8] to study the effect of higher surface roughness heights, which introduces greater instability in the boundary layer of circular cylinder. A detailed quantitative measurement of the flow field around the cylinder in moving ground using Lagrangian vortex method with two-dimensional modeling of roughness was carried out.…”

Section: Introductionmentioning

confidence: 99%

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Numerical experiments of the flow around a bluff body with and without roughness model near a moving wall

Pereira

Oliveira

Moraes

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

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Numerical tests at high Reynolds number flows were taken on circular cylinder placed near and parallel to a moving ground. A moving ground running at the same speed as the free stream eliminates the confusing effects of the boundary layer formed on the ground being, therefore, more effective to establish a better understanding of the relationship between complete vortex shedding suppression and surface roughness. A detailed quantitative measurement of the flow field around the cylinder using Lagrangian vortex method with roughness model was carried out. The effect of higher surface roughness heights is studied because it introduces greater instabilities in the boundary layer of bluff bodies. The purpose is to investigate supercritical flow patterns from subcritical Reynolds number flow simulations. The present results are compared against those measured for smooth cylinder under the same flow conditions. It is found that certain critical gap ratio between the rougher cylinder bottom and the moving wall significantly reduces the drag force. The lift force points away from the wall plane. The full vortex shedding suppression is successfully anticipated. In addition, the Strouhal number vanishes. The contribution of this research is to report that von Kámán-type vortex shedding totally ceases and instead two nearly parallel shear layers are formed behind the cylinder in moving ground when employing two-dimensional modeling of roughness. Previous numerical results for flow around smooth cylinder placed closer to the moving ground did not capture the behavior of Strouhal number equal to zero. Unfortunately, there is a lack of experimental results for rough cylinder near a moving wall, which motives the present study.

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Section: Introductionmentioning

confidence: 82%

Section: Methodsmentioning

confidence: 99%