Effect of different sized transverse square grooves on a turbulent boundary layer

Sutardi,; Ching, C.Y.

doi:10.1007/s00348-002-0556-y

Cited by 9 publications

(4 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hence, the wall shear stress (τ w ) is higher, of approximately 1%, for the grooved-wall case than that on the smooth-wall case. The validity of the use of mean velocity gradient at the wall to obtain wall shear stress has been approved by Sutardi [3] after the application of correction factor for mean velocity signal near the wall due to wall conduction effect as suggested by Lange et al [4] and Durst et al [5,6]. For better view, the mean velocity are plotted in the semi-log scale (see Figs.…”

Section: Streamwise Mean Velocitymentioning

confidence: 99%

See 1 more Smart Citation

Analysis of Turbulence Characteristics in the Laminar Sub-Layer Region of a Perturbed Turbulent Boundary Layer

Sutardi

Widodo

2016

AMM

View full text Add to dashboard Cite

Turbulent boundary layer plays an important role for generation of aerodynamic drag. Shear force and pressure force due to the presence of boundary layer separation from the body surface contribute to the total drag. Studies of drag reduction due the the boundary layer effect are continuously performed by many researchers. Present study is intended to evaluate the behaviour of the laminar sub-layer in a turbulent boundary layer using a hot-wire anemometer system. The study was conducted in a low-speed wind tunnel at a Reynolds number based on the momentum thickness of approximately Reθ = 1000. A smooth-flat plate and a plate with a single transverse square groove was used in the study of the boundary layer characteristics. The groove size of 10 mm x 10 mm was cut transversally across the test plate. The results show that no significant differences in the streamwise mean velocity, steamwise turbulence intensity, and velocity signals for the smooth-and grooved-wall cases. For the the energy spectra for the two cases, however, show significant differences.

show abstract

Section: Streamwise Mean Velocitymentioning

confidence: 99%

“…This size may be to small to have significant effect on the the mean velocity and turbulence intensity. Sutardi [3] showed that if the size of the groove was enlarged becomes twice (26 % of the δ 0 ), the effect of the groove on the the mean velocity and turbulence intensity becomes more pronounced.…”

Section: Turbulence Energy Spectramentioning

confidence: 99%

Analysis of Turbulence Characteristics in the Laminar Sub-Layer Region of a Perturbed Turbulent Boundary Layer

Sutardi

Widodo

2016

AMM

View full text Add to dashboard Cite

show abstract

“…Therefore, the best knowledge of the flow field around these cavities is of great importance. To understand the effect of the cavity size on a turbulent boundary layer, Sutardi and Ching [9] studied three different sized transverse square grooves (5, 10, and 20 mm). This allowed a comparison between results obtained by many authors for square cavities (L/H = 1).…”

Section: Introductionmentioning

confidence: 99%

Turbulent boundary layer over a deep cavity: friction coefficient and streamwise velocity components

Hassan¹,

Labraga²,

Keirsbulck³

2007

Can. J. Phys.

View full text Add to dashboard Cite

Deep cavities are present in car vehicles in numerous forms. Although drag downstream cavities have interested many authors, this aspect was never treated for particularly deep cavities. The objective of the present investigation is to study the effect of a deep cavity, characterized by its length-to-depth ratio L/H = 0.2, on both the skin friction coefficient and the statistic components of the streamwise velocity. Laser Doppler velocimetry (LDV) was used for the mean velocity and its statistic components measurements. Results obtained by other authors allowed a comparison between shallow and deep cavity configurations. The main conclusion is that with the same flow conditions, the drag increase downstream from the cavity is less important compared to the square cavity. A localized skewness coefficient decrease and a flatness coefficient increase could be related to intermittence ejection of flow from the downstream part of the cavity. This hypothesis was confirmed thanks to particle image velocimetry (PIV) measurements. Résumé :Les cavités profondes sont présentes dans les véhicules automobiles sous différents aspects. plusieurs auteurs se sont intéressés au frottement pariétal en aval d'une cavité rectangulaire. Cependant, cet aspect n'a jamais été abordé pour les cavités très profondes. L'objectif du présent article est d'étudier l'influence d'une cavité rectangulaire profonde, caractérisée par son rapport longueur sur profondeur L/H = 0, 2, sur le coefficient de frottement pariétal ainsi que sur les moments statistiques de la vitesse longitudinale. Les mesures de la vitesse moyenne ainsi que ses moments statistiques ont été réalisées grâce à la Vélocimétrie Laser Doppler (LDV). Nos résultats sont comparés avec ceux d'autres auteurs et montrent que l'augmentation du frottement pariétal en aval d'une cavité est moins importante lorsqu'il s'agit d'une cavité profonde. Un coefficient de dissymétrie (S u ) plus négatif et un facteur d'aplatissement (F u ) plus élevé en aval de la cavité pourront être expliqués par des éjections intermittentes de structures au niveau du bord de fuite de la cavité. Ces éjections ont été mises en évidence grâce aux mesures de vélocimétrie par image de particule PIV.

show abstract

“…[1], [2] 1 .8m in width and 1 .2m in height. One side of test was stuck to the wall of CWC, while a thin flat plate is attached to the Previous studies 3utliedthLother side to avoid the interferences by supporting strut and Previous studies [3], [4], [5] begins to show the meaningful results on the mechanism of flow interaction between outer flow and roughness elements. PIV ilumination system consists of a 6W Ar-Ion Laser, The present study selects the repeated 2-D rectangular fiber-optic cable and a probe with cylindrical lens for the shaped roughness elements mounted on flat plate for basic Laser sheet generation.…”

mentioning

confidence: 99%

Turbulent Flow over Two-Dimensional Rectangular-Shaped Roughness Elements with Various Spacings

Hyun

Suh

Kim

2006

OCEANS 2006 - Asia Pacific

View full text Add to dashboard Cite

The present study deals with the flow over a flat roughness to investigate the effects of the size of roughness plate with repeated roughness elements of 2-dimensional elements and the distance between them. Experiment was rectangular shape, which can be applied into the study on the performed in circulating water channel (CWC), and PIV natural geographical roughness and the turbulent flow on technique was employed to measure the mean and turbulence roughened solid surface. Experiment was performed using PIV characteristics around the roughened surface of 3 different technique in the circulating water channel. Results showed that . F the flow over roughness elements was characterized by the high roughness spacings. Further analyses using the law-of-the shear flow emanating from top of roughness element and the wall and the boundary layer integral parameters were made to recirculating region formed at the trough of two roughness quantifytheeffectofthechangeofroughnessspacing. elements. It was also confirmed that k-type roughness is certainly a more effective means than d-type roughness in thickening the viscous layer. In general, the ratio between the 1 MODEL,INSTRUMENTATION AND PIV spacing and the height of roughness elements plays a crucial role TECHNIQUES in developing the flow pattern near wall surface. The repeated readjustable rectangular-shaped roughness elements were attached to the flat plate made of PVC, where I. INTRODUCTION the number of elements varies from 7 to 22 depending on Flow in nature is inherently turbulent with a variety of their spacings. Measuring location was 7500 downstream of roughness elements such as oceanic and seabed roughnesses plate in length from leading edge of plate to achieve the better as well as atmospheric macro-/micro-scale roughnesses. periodicity of flow. A rectangular element has the height (H) Effects of surface roughness include the resistance increment of 20mm and w/H=1 where w is the width of element. Three on body, change of seabed shape and sediment transport etc. different distances between elements were chosen: s/H = 3.5, Relatively simple elements like rectangular-shaped or wavy 7, 14, where s denotes the roughness spacing. Model was surfaces were used for fundamental study to elucidate the installed inside CWC with its dimension of 5m in length, effect of roughness on boundary layer flow. [1], [2] 1 .8m in width and 1 .2m in height. One side of test was stuck to the wall of CWC, while a thin flat plate is attached to the Previous studies 3utliedthLother side to avoid the interferences by supporting strut and Previous studies [3], [4], [5] utilized the Law-of-theother stuffs. Freestream velocity U0was set to 0.24m/s so that Wall, which is the only available practical way to study the change of flow characteristics due to various kinds of Reynolds number based on freestream velocity and roughness cnane o flw caraterst1c au tovarousKmo ot height was 4210. Flow periodicity between adjacent roughness such as the well-known sand grain roughness, 2-D roughn was esim ...

show abstract

Effect of different sized transverse square grooves on a turbulent boundary layer

Cited by 9 publications

References 18 publications

Analysis of Turbulence Characteristics in the Laminar Sub-Layer Region of a Perturbed Turbulent Boundary Layer

Analysis of Turbulence Characteristics in the Laminar Sub-Layer Region of a Perturbed Turbulent Boundary Layer

Turbulent boundary layer over a deep cavity: friction coefficient and streamwise velocity components

Turbulent Flow over Two-Dimensional Rectangular-Shaped Roughness Elements with Various Spacings

Contact Info

Product

Resources

About