The symmetric turbulent wake of a flat plate

Ramaprian, B. R.; Patel, V. C.; Sastry, M. S.

doi:10.2514/3.7972

Cited by 70 publications

(28 citation statements)

References 5 publications

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“…The extent of the inner wake can be identified as the region where the velocity profile deviates from the boundary-Iayer-wall-law profile, and in the following this position will be indicated by y = 0i" This definition of the inner wake edge is different from that of Andreopoulos & Bradshaw (1980) which is based on the intermittency of heated fluid coming from one side of the plate. At downstream positions, the changes 0, data of Ramaprian et al (1982).…”

Section: Mean-velocity Resultsmentioning

confidence: 99%

“…If the view of earlier authors is accepted, the central region of the near wake should be Reynolds-number-independent, just like the inner layers of the upstream boundary layers. In fact, this similarity in terms of the wall variables has been the basis for correlating data (Andreopoulos & Bradshaw 1980;Ramaprian et al 1982) and the assumption in theoretical (Alber 1980) and computational analyses (Cebeci et ai. 1979;Patel & Chen 1989) of flat-plate wakes.…”

Section: Introductionmentioning

confidence: 82%

“…It is the view of most authors (Bradshaw 1970;Andreopoulos & Bradshaw 1980;Alber 1980;Ramaprian, Patel & Sastry 1982) that, in the near wake of a flat plate, the inner and outer layers of the boundary layers at the trailing edge do not change A. Nakayama and B. Liu Badri Narayanan et al 1985, Rfl = 1200, slightly asymmetric -the edge-velocity ratio is 0.96.…”

Section: Introductionmentioning

confidence: 98%

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The turbulent near wake of a flat plate at low Reynolds number

Nakayama¹,

Liu

1990

J. Fluid Mech.

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Mean-velocity and turbulence measurements have been made in the turbulent near wake of a flat plate at various Reynolds numbers in order to investigate the low-Reynolds-number effects in this region. The results indicate that the low-Reynolds-number effects are significant enough to partially explain the discrepancies in the existing mean-velocity data. It has been found that, while the Reynolds-number-independent, inner-law similarity of the boundary layers continues to exist, the width of the inner wake that develops within the inner-law region scales with the outer variable. Therefore, the mean velocity near the wake centreline depends on the Reynolds number. It is conjectured that this is due to the influence of the large eddies of the outer layer on the spreading of the inner wake.Measured turbulence quantities indicate that sudden changes occurring just downstream of the trailing edge are independent of the Reynolds number, but the subsequent development of the turbulent stress profiles depends on the Reynolds number. The Reynolds shear stress and the mean-velocity profiles within the inner wake show approximate similarity.

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Section: Mean-velocity Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 98%

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The turbulent near wake of a flat plate at low Reynolds number

Nakayama¹,

Liu

1990

J. Fluid Mech.

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“…where υ T is the turbulent eddy viscosity. The value of ∞ is assumed to be 0.032 based on the work of Ramaprian et al (1982) and Pot (1979). Figure 9 illustrates boundary layer and wake parameters are shown in a definition sketch.…”

Section: Flow Fieldmentioning

confidence: 99%

Effects of waves and the free surface on a surface-piercing flat-plate turbulent boundary layer and wake

Marquardt¹

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__________________________________ Pablo Carrica ii To my parents iii ACKNOWLEDGMENTS I wish to acknowledge all of those who have lent their time, labor, and expertise in order to complete the experiments and this thesis. This study reflects not only my work but that of a collaborative effort. I thank my advisor Dr. Fredrick Stern for the opportunity to pursue higher education and his assistance along the way. I am equally grateful for the help and advice I received from Dr. Joseph Longo, without whom, much of this work would not have been completed. My appreciation for these gentlemen surpasses all others-for the lessons they have taught me extend beyond fluid mechanics. I would also like to express my appreciation to Dr. Pablo Carrica for serving on my thesis committee. Hyunse Yoon and Dong Hoon Kang graciously provided the necessary tools to process data. Without their assistance, various calculations and plots would have been rough at best. Several students have assisted acquiring data and maintaining the laboratory in ship shape fashion, they include Chelsea Cross, Brian Jaffe, Adam Keen, Andrew Porter, and Michael Skrypczak. Their help aside, they have made the time spent in the laboratory far more enjoyable. The IT support personnel and the Model Annex personnel have to be commended for their prompt response servicing computerized controls and equipment. Finally, I like to thank any other person who contributed to the completion of this thesis and is not specifically mentioned. iv ABSTRACT Results are presented for towing tank experiments of a surface-piercing flat plate with superimposed Stokes wave in order to examine free surface and wave effects on the boundary layer and wake. Measurements with servo wave gauges are made to characterize the Stokes-wave wave field in terms of its two-dimensionality, amplitude, and wavelength. Flow field measurements using stereo particle image velocimetry are used to identify the boundary layer and wake velocities. Particular attention is drawn to the juncture region to resolve the complex and poorly understood secondary flow patterns. Four test cases are presented (1) flat free surface without plate, (2) Stokes-wave without plate, (3) flat free surface with plate, and (4) Stokes-wave with plate; the cases were chosen in order to isolate and identify the performance of the velocimeter system, Stokes-wave flow field, free-surface effects, and combined Stokes-wave and free surface effects, respectively. All cases are conducted at Froude numbers of Fn = 0.4, lengthbased Reynolds number of Re = 1.64×10 6 , and momentum thickness-based Reynolds number of about Re θ = 4000. Results show, as expected, that the free surface effectspenetrate to a depth slightly greater than the boundary layer thickness and wave effects diminish at roughly one half the wavelength. The juncture region flow was resolved to levels that far exceed previous towing tank experiments, but leave more to be desired.The data and analysis are important, not only from a scientific perspective, but have a prac...

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“…experimental information on the turbulent wake of a flat plate suggest that the wake can be divided into three regions: the near wake, intermediate region, and the asymptotic far wake[22]. The near wake occupies a very small region down stream of the trailing edge, where the logarithmic layers of the oncoming boundary layers are destroyed.…”

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confidence: 99%

Computation of turbulent flow about unconventional airfoil shapes

Ahmed

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The symmetric turbulent wake of a flat plate

Cited by 70 publications

References 5 publications

The turbulent near wake of a flat plate at low Reynolds number

The turbulent near wake of a flat plate at low Reynolds number

Effects of waves and the free surface on a surface-piercing flat-plate turbulent boundary layer and wake

Computation of turbulent flow about unconventional airfoil shapes

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