Experimental investigation on the combined effects of surface roughness and corner radius for square cylinders at high Reynolds numbers up to 107

Hinsberg, Nils Paul van; Schewe, G.; Jacobs, Markus

doi:10.1016/j.jweia.2017.12.003

Cited by 34 publications

(17 citation statements)

References 40 publications

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“…Early experimental investigations by Delany and Sorensen [4] and Polhamus [9] on smooth squared prisms with rounded edges in cross-flow showed that an increase in the edge radius has a positive effect on the aerodynamic loading, as it lowers the drag force at equal Reynolds number on such prisms and shifts both the critical and supercritical flow states to lower Reynolds numbers. These observations were later confirmed through wind tunnel studies on smooth rounded square prisms by Tamura et al [13], Carassale et al [3], and van Hinsberg et al [5], who also reported a decrease of the fluctuating lift coefficient and an increase in the vortex shedding frequency compared with their sharp-edged counterparts. They concluded that the rounded surface of the prism allows the movements of the boundary layer transition and primary separation points, as well as of the shear layer reattachment and secondary turbulent boundary layer separation points with Reynolds number similarly to circular cylinders, although for the former their movements are less pronounced.…”

Section: Introductionmentioning

confidence: 61%

Loading on rounded square foundation elements of offshore structures with marine growth at incidence

Frede¹,

Hinsberg²

2020

Australasian Fluid Mechanics Conference (AFMC)

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A systematic wind tunnel study is performed to identify the mean and fluctuating loads experienced by a 2D square prism with non-dimensional rounded edges of r/D = 0.16 and covered with hard marine fouling for Reynolds numbers between 70,000 and 8 million. The incidence angle is varied from α = −45 • to 3.25 • with increments of 3.25 • and 6.5 • . The critical angle of incidence, at which a reattachment of the free shear layer takes place on the lateral windward directed side surface, is found at α cr = −6.5 • . For α < α cr two opposite trends -governed by the Reynolds number -of the mean drag coefficient, the r.m.s. of the lift fluctuations, and the Strouhal number are obtained. On the contrary, all aerodynamic parameters are relatively Reynolds-number independent for α > α cr . For the latter angles of incidence, a decrease towards −45 • induces higher values of C D and the r.m.s. of the lift fluctuations, as well as lower Strouhal numbers and mean lift forces.

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Section: Introductionmentioning

confidence: 61%

Loading on rounded square foundation elements of offshore structures with marine growth at incidence

Frede¹,

Hinsberg²

2020

Australasian Fluid Mechanics Conference (AFMC)

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“…Furthermore, decreasing the angle of incidence to a negative value causes the drag force, the Strouhal number and the base pressure to increase. In another research study, van Hinsberg et al 140 proved that higher vortex shedding frequency at all flow regimes is yielded with a larger corner radius. Hu and Zhou 141 evaluated the flow characteristics around a square cylinder with some corners rounded.…”

Section: Square Cylindersmentioning

confidence: 94%

A review of experiments on stationary bluff body wakes

Feshalami

Scarano

et al. 2022

Physics of Fluids

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Experimental studies dealing with the wake of isolated stationary bluff-bodies are reviewed. After briefly recalling the pioneering works in this domain, the paper focuses on recent research conducted with the latest experimental methods and techniques. The review encompasses a range of topics, including, the effects of bluff-body geometry (non-circular cross sections and nonuniformity in spanwise direction), steady and unsteady (periodic and non-periodic) inflow conditions; surface proximity (rigid wall, confinement and water free surface) and non-Newtonian fluids. Focus is brought to the flow physics of the wakes, including especially the complex threedimensional and oscillatory behaviours induced by the periodic vortex shedding phenomenon. The paper aims to offer a critical and systematic review of new knowledge and findings on the subject area, as well as emerging? and the most frequently adopted experimental techniques. The review also helps identifying knowledge gaps in the literature that need to be addressed in future investigations.

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“…Reynolds number and surface roughness height, by varying the total air pressure, while keeping all other boundary conditions like cylinder diameter, surface texture and height, object dimensions and free-stream turbulence intensity constant. The data of two previous experimental investigations, conducted in this wind tunnel, on the flow around 2D smooth and rough circular cylinders (van Hinsberg (2015)) and square-section prisms with non-dimensional edge radii of r/D = 0.29 and 0.16 (van Hinsberg et al (2018)) can nevertheless be used to make a statement on the presumed aerostatic behaviour of smooth sharp-edged square prisms at ultra-high Reynolds numbers beyond Re D = 10 7 . Both previous experiments have shown that an increase in surface roughness height from k s /D = 10 −5 (smooth) to k s /D = 10 −3 (rough) results in a shift of the boundaries of all flow regimes to lower Reynolds numbers by a factor of Re D,smooth /Re D,rough =1.8 for circular cylinders (r/D = 0.5) and by a factor of Re D,smooth /Re D,rough = 2.9 and 4.1 for square-section prisms with edge radii of r/D = 0.29 and 0.16, respectively.…”

Section: Stmentioning

confidence: 96%

Aerodynamics of smooth and rough square-section prisms at incidence in very high Reynolds-number cross-flows

Hinsberg

2021

Exp Fluids

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The aerodynamics of smooth and slightly rough prisms with square cross-sections and sharp edges is investigated through wind tunnel experiments. Mean and fluctuating forces, the mean pitch moment, Strouhal numbers, the mean surface pressures and the mean wake profiles in the mid-span cross-section of the prism are recorded simultaneously for Reynolds numbers between 1$$\times$$ × 10$$^{5}$$ 5 $$\le$$ ≤ Re$$_{D}$$ D $$\le$$ ≤ 1$$\times$$ × 10$$^{7}$$ 7 . For the smooth prism with $$k_s$$ k s /D = 4$$\times$$ × 10$$^{-5}$$ - 5 , tests were performed at three angles of incidence, i.e. $$\alpha$$ α = 0$$^{\circ }$$ ∘ , −22.5$$^{\circ }$$ ∘ and −45$$^{\circ }$$ ∘ , whereas only both “symmetric” angles were studied for its slightly rough counterpart with $$k_s$$ k s /D = 1$$\times$$ × 10$$^{-3}$$ - 3 . First-time experimental proof is given that, within the accuracy of the data, no significant variation with Reynolds number occurs for all mean and fluctuating aerodynamic coefficients of smooth square prisms up to Reynolds numbers as high as $$\mathcal {O}$$ O (10$$^{7}$$ 7 ). This Reynolds-number independent behaviour applies to the Strouhal number and the wake profile as well. In contrast to what is known from square prisms with rounded edges and circular cylinders, an increase in surface roughness height by a factor 25 on the current sharp-edged square prism does not lead to any notable effects on the surface boundary layer and thus on the prism’s aerodynamics. For both prisms, distinct changes in the aerostatics between the various angles of incidence are seen to take place though. Graphic abstract

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Experimental investigation on the combined effects of surface roughness and corner radius for square cylinders at high Reynolds numbers up to 107

Cited by 34 publications

References 40 publications

Loading on rounded square foundation elements of offshore structures with marine growth at incidence

Loading on rounded square foundation elements of offshore structures with marine growth at incidence

A review of experiments on stationary bluff body wakes

Aerodynamics of smooth and rough square-section prisms at incidence in very high Reynolds-number cross-flows

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