Measurements in the thick axisymmetric turbulent boundary layer near the tail of a body of revolution

Patel, V. C.; Nakayama, A.; Damian, R

doi:10.1017/s0022112074001170

Cited by 53 publications

(31 citation statements)

References 7 publications

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“…Jiménez et al (2010a,b) attributed it to the thick boundary layer developing along the stern of the DSub model. This is consistent with observations in earlier experiments by Patel, Nakayama & Damian (1974) and Merz, Yi & Przirembel (1986). In figure 14 the averaged turbulent kinetic energy, k, is shown at three different meridian planes up…”

Section: Bimodal Behaviour Of the Wake And Effect Of The Finssupporting

confidence: 90%

A numerical investigation of the wake of an axisymmetric body with appendages

Posa

Balaras

2016

J. Fluid Mech.

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We report wall-resolved large-eddy simulations of an axisymmetric body of revolution with appendages. The geometry is that of the DARPA SUBOFF body at 0 yaw angle and a Reynolds number equal to Re L = 1.2 × 10 6 (based on the free-stream velocity and the length of the body). The computational grid, composed of approximately 3 billion nodes, is designed to capture all essential flow features, including the turbulent boundary layers on the surface of the body. Our results are in good agreement with measurements available in the literature. It is shown that the wake of the body is affected mainly by the shear layer from the trailing edge of the fins and the turbulent boundary layer growing along the stern, while the influence of the wake of the sail is minimal. In agreement with the reference experiments, a bimodal behaviour for the turbulent stresses is observed in the wake. This is due to the displacement of the maximum of turbulent kinetic energy away from the wall along the surface of the stern, where the boundary layer is subjected to strong adverse pressure gradients. The junction flows, produced by the interaction of the boundary layer with the leading edge of the fins, enhance this bimodal pattern, feeding additional turbulence in the boundary layer and the downstream wake. The evolution of the wake towards selfsimilarity is also investigated up to nine diameters downstream of the tail. We found the mean flow approaches this condition, while its development is delayed by the wake of the appendages, especially by the flow coming from the tip of the fins. However, the width of the wake and its maximum momentum deficit follow the expected powerlaw behaviour on the side away from the sail. The second-order statistics, on the other hand, are still far from self-similarity, which is consistent with experimental observations in the literature.

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Section: Bimodal Behaviour Of the Wake And Effect Of The Finssupporting

confidence: 90%

A numerical investigation of the wake of an axisymmetric body with appendages

Posa

Balaras

2016

J. Fluid Mech.

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“…The pressure then decreases over the region of convex curvature near the start of the stern taper, before increasing over the region of concave curvature near the end of the stern. The concave portion of the stern has been identified as a region where the boundary-layer thickens rapidly due to a significant static pressure variation across the boundary layer (Patel, Nakayama & Damian 1974;Huang et al 1992). Figure 6.…”

Section: Resultsmentioning

confidence: 99%

The intermediate wake of a body of revolution at high Reynolds numbers

2010

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Results are presented on the flow field downstream of a body of revolution for Reynolds numbers based on a model length ranging from 1.1 × 106 to 67 × 106. The maximum Reynolds number is more than an order of magnitude larger than that obtained in previous laboratory wake studies. Measurements are taken in the intermediate wake at locations 3, 6, 9, 12 and 15 diameters downstream from the stern in the midline plane. The model is based on an idealized submarine shape (DARPA SUBOFF), and it is mounted in a wind tunnel on a support shaped like a semi-infinite sail. The mean velocity distributions on the side opposite the support demonstrate self-similarity at all locations and Reynolds numbers, whereas the mean velocity distribution on the side of the support displays significant effects of the support wake. None of the Reynolds stress distributions of the flow attain self-similarity, and for all except the lowest Reynolds number, the support introduces a significant asymmetry into the wake which results in a decrease in the radial and streamwise turbulence intensities on the support side. The distributions continue to evolve with downstream position and Reynolds number, although a slow approach to the expected asymptotic behaviour is observed with increasing distance downstream.

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“…In the plots of spectra, the frequency /has been normalised as kO where k is the wave number 2TrflU x and the spectral density as Q(k) = (IV27T0) E(f)luT, so that 8 / <&(k)dk=\ (10) The spectral distributions at large y/0 (Figs. 24,25) indicate Reynolds number independence when scaled on 17, and 0. In these distributions there is no sub-range where the spectrum has any extended power law variation in k, such as k~5 13 .…”

Section: Turbulence Measurementsmentioning

confidence: 99%

The thick turbulent boundary layer on a long fine cylinder in axial flow

1984

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SummaryTransverse curvature effects in axi-symmetric flow on a circulai cylinder are discussed and it is deduced that for small δ/a, where δ is the boundary layer thickness and a is the cylinder radius, transverse curvature effects are small, for δ/a = 0(1) the effect is felt mainly in the outer region and for δ/a » 1, both the inner and the outer regions are affected. It is argued that the last case can only be achieved experimentally in the laboratory if the radius Reynolds number Ra= U1a/v is small and the streamwise Reynolds number Rx=U1xlv is large, implying x/a large. New experimental data are presented for this case. The data show that both the mean and turbulent flow field scale on outer variables throughout the layer and, for Ra≥455, exhibit Reynolds number independence. No logarithmic region is found in the mean profiles, a result which is echoed by the absence of a shoulder in the streamwise turbulence profiles which clearly evidence that the flow in the layer is fully turbulent. A flow model is suggested, in physical terms, to explain the very high turbulence levels found close to the cylinder at values of Ra which should, according to stability theory, be bordering on laminar flow.

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Measurements in the thick axisymmetric turbulent boundary layer near the tail of a body of revolution

Cited by 53 publications

References 7 publications

A numerical investigation of the wake of an axisymmetric body with appendages

A numerical investigation of the wake of an axisymmetric body with appendages

The intermediate wake of a body of revolution at high Reynolds numbers

The thick turbulent boundary layer on a long fine cylinder in axial flow

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