Flow over Rectangular Cylinders Immersed in a Turbulent Boundary Layer : Part 1, Correlation between Pressure Drag and Boundary-Layer Characteristics

Arie, Mikio; Kiya, Masaru; Tamura, Hisataka; Kanayama, Yukio

doi:10.1299/jsme1958.18.1260

Cited by 10 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The focus of these studies was to measure the form drag and pressure distributions due to these obstacles (Arie et al, 1975aand 1975b, Taniguchi et al, 1981, Sakamato et al, 1982, Sakamato, 1985. Their efforts have yielded a large amount of experimental data on flow past obstacles such as rectangular cylinders, cubes and circular cylinders.…”

Section: Turbulent Flow Past Surface-mounted Obstaclesmentioning

confidence: 99%

Structure of 2-D and 3-D Turbulent Boundary Layers with Sparsely Distributed Roughness Elements

George¹

2005

View full text Add to dashboard Cite

The present study deals with the effects of sparsely distributed three-dimensional elements on two-dimensional (2-D) and three-dimensional (3-D) turbulent boundary layers (TBL) such as those that occur on submarines, ship hulls, etc. This study was achieved in three parts: Part 1 dealt with the cylinders when placed individually in the turbulent boundary layers, thereby considering the effect of a single perturbation on the TBL; Part 2 considered the effects when the same individual elements were placed in a sparse and regular distribution, thus studying the response of the flow to a sequence of perturbations; and in Part 3, the distributions were subjected to 3-D turbulent boundary layers, thus examining the effects of streamwise and spanwise pressure gradients on the same perturbed flows as considered in Part 2. The 3-D turbulent boundary layers were generated by an idealized wing-body junction flow.Detailed 3-velocity-component Laser-Doppler Velocimetry (LDV) and other measurements were carried out to understand and describe the rough-wall flow structure. The measurements include mean velocities, turbulence quantities (Reynolds stresses and triple products), skin friction, surface pressure and oil flow visualizations in 2-D and 3-D rough-wall flows for Reynolds numbers, based on momentum thickness, greater than 7000. Very uniform circular cylindrical roughness elements of 0.38mm, 0.76mm and 1.52mm height (k) were used in square and diagonal patterns, yielding six different roughness geometries of rough-wall surface. For the 2-D rough-wall flows, the roughness Reynolds numbers, + k , based on the element height (k) and the friction velocity ( τ U ), range from 26 to 131. Results for the 2-D rough-wall flows reveal that the velocity-defect law is similar for both smooth and rough surfaces, and the semi-logarithmic velocity-distribution curve is shifted by an amountdepending on the height of the roughness element, showing thatis a function of + k and the wall geometry. For the 3-D flows, the data show that the surface pressure gradient is not strongly influenced by the roughness elements. Higher roughness elements cause greater turbulence intensities near the wall, which cause the pressure-driven mean flow three-dimensionality to propagate or diffuse more rapidly from the wall region. In general, for both 2-D and 3-D rough-wall TBL, the differences between the two roughness patterns (straight and diagonal), as regards the mean velocities and the Reynolds stresses, are limited to about 3 roughness element heights from the wall.For the single elements, the values of + k range from 23 to 92. The study on single elements revealed that the separated shear layers emanating from the top of the elements form a pair of counter rotating vortices that dominate the downstream flow structure. These vortices, termed as the roughness top vortex structure (RTVS), in conjunction with the mean flow, forced over and around the elements, are responsible for the production of large Reynolds stresses in the neighborhood of th...

show abstract

Section: Turbulent Flow Past Surface-mounted Obstaclesmentioning

confidence: 99%

Structure of 2-D and 3-D Turbulent Boundary Layers with Sparsely Distributed Roughness Elements

George¹

2005

View full text Add to dashboard Cite

show abstract

“…. • At the inlet, a log profile for the fully developed boundary layer flow is used for the streamwise velocity, which is obtained by curve fitting of the experimental boundary layer profile reported by Arie et al (1975). The vertical and spanwise velocities are set to zero.…”

Section: Computational Overviewmentioning

confidence: 99%

“…The vertical and spanwise velocities are set to zero. A boundary layer thickness of d/H = 0.73 is employed, which is the same as that in the experiments carried out by Arie et al (1975). A zero normal gradient is applied for the pressure at the inlet.…”

Section: Computational Overviewmentioning

confidence: 99%

“…There are many experimental studies carried out to analyse the high Reynolds flow over surface-mounted structures over decades. Arie et al (1975) studied the flow over wall-mounted rectangular cylinders subjected to turbulent boundary layer flow and concluded that the pressure coefficient on the structure surface is correlated with the thickness of the boundary layer. Fully developed turbulent channel flow around prismatic obstacles was investigated by Martinuzzi and Tropea (1993) and it was found that there is a nominally two-dimensional middle region in the wake about the plane of symmetry behind the structures with an aspect ratio larger than 6.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Three-dimensional numerical simulations and proper orthogonal decomposition analysis of flow over different bottom-mounted ribs

Fraga

Yin

Ong

2021

Ships and Offshore Structures

View full text Add to dashboard Cite

Turbulent flow over bottom-mounted ribs is investigated using three-dimensional (3D) Spalart-Allmaras Delayed Detached-Eddy Simulations (SADDES). The ribs are subjected to a boundary layer flow with a thickness of δ/H=0.73 at Re=1 * 106(Re=U∞H/ν), where U∞ is the free stream velocity, H is the rib height and ν is the fluid kinematic viscosity. Mesh and time step convergence studies are conducted to determine the grid and time step resolution. The numerical model is validated against the previous published experimental data and numerical results. The effects of different ribs geometries on drag and lift coefficients, the wake flow structures, and the dominant frequencies are discussed. Dominant flow features are investigated by carrying out Proper Orthogonal Decomposition (POD) and quadrant analysis of velocities and pressure in the wake flow.

show abstract

“…It has been suggested that the ratio of the streamwise extent of the step to its height (L/h) must be sufficiently large (L/h > 10) for the recirculation region over the step to be considered truly isolated. [29,30] Thus, investigations by Agelinchaab and Tachie, [7] Bergeles and Athanassiadis, [29] Arie et al [31] and others that do not meet this criterion are excluded from Table 1. The effects of aspect ratio on separated shear flows have been thoroughly investigated in connection with potential sidewall effects on the reattachment length.…”

Section: Introductionmentioning

confidence: 99%

Effects of upstream roughness and Reynolds number on separated and reattached turbulent flow

Essel

Nematollahi

Thacher

et al. 2015

Journal of Turbulence

View full text Add to dashboard Cite

This paper presents experimental investigation of upstream roughness and Reynolds number effects on the recirculation region over a smooth forward facing step. The upstream rough wall was produced from 1.5 mm sand grains and the Reynolds number based on step height, Re h , was varied from 2040 to 9130 for both the upstream smooth and rough walls. For the smooth wall, the reattachment length increased monotonically with Re h to an asymptotic value of 2.2 step heights for Re h ≥ 6380. Upstream roughness reduced the reattachment length by 44% because of larger momentum deficit and higher turbulence level in the rough wall boundary layer. The mean velocities and Reynolds stresses were also reduced by roughness. The Reynolds shear stress and production of turbulent kinetic energy showed high negative values at the leading edge of the step indicating counter-gradient diffusion. The implications of these results for standard eddy viscosity models are discussed.

show abstract

Flow over Rectangular Cylinders Immersed in a Turbulent Boundary Layer : Part 1, Correlation between Pressure Drag and Boundary-Layer Characteristics

Cited by 10 publications

References 0 publications

Structure of 2-D and 3-D Turbulent Boundary Layers with Sparsely Distributed Roughness Elements

Structure of 2-D and 3-D Turbulent Boundary Layers with Sparsely Distributed Roughness Elements

Three-dimensional numerical simulations and proper orthogonal decomposition analysis of flow over different bottom-mounted ribs

Effects of upstream roughness and Reynolds number on separated and reattached turbulent flow

Contact Info

Product

Resources

About