Experimental study on the turbulent boundary layer flow over riblets surface

Wang, Jinjun; Lan, Shilong; Guang, Chen

doi:10.1016/s0169-5983(00)00009-5

Cited by 60 publications

(24 citation statements)

References 17 publications

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“…All the data presented in Figs4, 5, 6 and7 at each position (x), indicate that the logarithm laws AlogY + +B, for the smooth case is different from the one for the L-shaped riblets. The same behavior was well confirmed by Wang, Lan and Chen, 2000 [18] and by Brima, Atmani and Achour, 2006 [19] for the V-riblets surfaces. The theoretical shear stress values for smooth and riblets surfaces are given in Tables 1 and 2 Tables 1 and 2; we can observe that the ribbed surface boundary layer thickness is thinner than that of the smooth one.…”

Section: Theoretical Approachsupporting

confidence: 81%

Theoretical Approach on the Study of Turbulent Water Flow over Smooth and L-shaped Riblets Surfaces

Brima

Atmani

Achour

2008

Inter J Fluid Mech Res

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A very important research effort has been developed at many world laboratories these last years in order to reduce the friction drag. For the aircraft and the submarine applications, friction contributes respectively for about 50% and 70% of the total resistance. The use of surface modifications riblets as a means of reducing viscous drag on a body has potential aerodynamic and hydrodynamic applications. In the present study, the theoretical approach allow to determine the velocity field, the wall shear stress, the local skin friction, the boundary layer thickness, the laminar sub layer thickness and the dimensionless drag coefficient. The results found, indicate that the presence of L-shaped riblets surfaces provide changes in the characteristics of the turbulent boundary layer, which are in favor of wall skin friction.KEYWORDS: turbulent flow, riblets, shear stress, layer thickness, friction reduction. RESUMEUn effort très important a été fourni ces dernières années à travers les laboratoires du monde dans le domaine de la réduction de traînée visqueuse. Pour les avions de transport et les sous marins, la traînée visqueuse contribue respectivement d'environ 50% à 70% de la résistance totale. L'utilisation des modifications au niveau de la surface est un moyen efficace pour réduire la traînée visqueuse dans les applications aérodynamique et hydrodynamique. Dans cette étude, l'approche théorique permis de déterminer le champ de vitesse, la contrainte de cisaillement à la paroi, le coefficient de frottement local, l'épaisseur de la couche limite, l'épaisseur de la sous couche visqueuse et finalement le coefficient non dimensionnel de traînée sont représentés. Les résultats trouvés ont montré que la présence des rainures en lames " L " fournie des changements dans les caractéristiques de la couche limite turbulente, qui sont en faveur du coefficient de frottement pariétal.MOTS CLES : écoulement turbulent, riblets, contrainte de cisaillement, épaisseur de couche, réduction de frottement.

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Section: Theoretical Approachsupporting

confidence: 81%

Theoretical Approach on the Study of Turbulent Water Flow over Smooth and L-shaped Riblets Surfaces

Brima

Atmani

Achour

2008

Inter J Fluid Mech Res

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“…Skin friction drag shares a very quotient in the total drag, even over 60% or 80% for the streamlined bodies and 100% for pipe transportation [3,4]. Therefore, skin friction drag reduction is a key for drag reduction.…”

Section: Introductionmentioning

confidence: 99%

Drag Reduction by Microvortexes in Transverse Microgrooves

Bao

Wang

Zhou

et al. 2014

Advances in Mechanical Engineering

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A transverse microgrooved surface was employed here to reduce the surface drag force by creating a slippage in bottom layer in turbulent boundary layer. A detailed simulation and experimental investigation on drag reduction by transverse microgrooves were given. The computational fluid dynamics simulation, using RNG k-turbulent model, showed that the vortexes were formed in the grooves and they were a main reason for the drag reduction. On the upside of the vortex, the revolving direction was consistent with the main flow, which decreased the flow shear stress by declining the velocity gradient. The experiments were carried out in a high-speed water tunnel with flow velocity varying from 17 to 19 m/s. The experimental results showed that the drag reduction was about 13%. Therefore, the computational and experimental results were cross-checked and consistent with each other to prove that the presented approach achieved effective drag reduction underwater.

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“…Fig.5 shows that there are nearly double streaks on the smooth surface than on the groove surface. This conclusion is oppositive with the result in [6]. Wang et alE61 found that the average spacing between the neighbour streaks was shorter on one kind of groove surface.…”

Section: Flow Structures In the Sublayermentioning

confidence: 79%

Experimental study of turbulent boundary layers on groove/smooth flat surfaces

Tian

Wang

2005

J. of Therm. Sci.

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This paper presents an experimental investigation of the turbulent boundary layers on both groove and smooth fiat surfaces. The flow structures were shown in a water tunnel using the hydrogen-bubble flow visualization technique. The measurement results indicate that: (1) the grooves can effectively reduce accumulation of low-speed fluids, decrease the number of the low-speed streaks and depress oscillation of the streaks in the sublayer; (2) the grooves can restrain forming of the horseshoe vortices in the buffer region; (3) the grooves bate oscillation and kinking of the quasi-streamwise vortices and restrain production of the hairpin vortices and the ring vortices, reducing both frequency and intensity of the turbulence bursting; (4) the grooves directly affect the flow structures in the sublayer of the boundary layer and then modulate the flow field up to the buffer region and the logarithmic region by restraining development and interaction of the vortices.

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Experimental study on the turbulent boundary layer flow over riblets surface

Cited by 60 publications

References 17 publications

Theoretical Approach on the Study of Turbulent Water Flow over Smooth and L-shaped Riblets Surfaces

Theoretical Approach on the Study of Turbulent Water Flow over Smooth and L-shaped Riblets Surfaces

Drag Reduction by Microvortexes in Transverse Microgrooves

Experimental study of turbulent boundary layers on groove/smooth flat surfaces

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