Momentum and heat transport in the turbulent intermediate wake of a circular cylinder

Matsumura, Masanori; Antonia, R. A.

doi:10.1017/s0022112093001600

Cited by 112 publications

(79 citation statements)

References 9 publications

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“…The appearance of theθ * contours for T /d = ∞ (figure 9c) is similar to that reported by Matsumura & Antonia (1993) and need not be discussed further. For the two-cylinder case, the region near the vortex centre coincides with the positive large-θ * contours ( figure 9f, i ), apparently resulting from the association of heat with vortices.…”

Section: The Velocity and Temperature Fluctuationssupporting

confidence: 82%

“…Their experimental uncertainties are estimated to be 4%, 6% and 5%, respectively. If re-normalized by U 1 instead of U ∞ , the single-cylinder data (not shown here) agree both qualitatively and quantitatively with those of Matsumura & Antonia (1993), thus providing a validation of the present measurement. A number of observations can be made.…”

Section: Coherent Contribution To Reynolds Stresses and Heat Fluxessupporting

confidence: 79%

“…Briefly, the v-signals from the two probes were both digitally band-pass filtered with the centre frequency set at f s . The low-and high-pass frequencies were chosen to be the same as f s , that is, a zero band-pass width was chosen, following Matsumura & Antonia (1993). This choice allowed a better focus on the vortical structures at f s .…”

Section: Phase and Structural Averagingmentioning

confidence: 99%

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The turbulent wake of two side-by-side circular cylinders

Zhou¹,

Zhang²,

Yiu³

2002

J. Fluid Mech.

172

134

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This work is an experimental study of the turbulent vortex structures, and heat and momentum transport in the wake of two side-by-side circular cylinders. The spacing T between the cylinder axes was varied from 1.5d to 3d (d is the cylinder diameter). Both cylinders were slightly heated. A movable three-wire probe measured the velocity and temperature fluctuations, and an X-wire provided a phase reference. Measurements were conducted at x/d = 10, 20 and 40 at a Reynolds number of 5800 (based on d and the free-stream velocity U ∞ ). At T /d = 1.5, the phase-averaged velocity and temperature fields display a single vortex street. The two rows of vortices exhibit a significant difference in the maximum vorticity, size and lateral distance from the flow centreline. As T /d is increased to 3.0, the flow is totally different. Two antiphase streets occur initially. They are less stable, with vortices weakening faster, than the street at T /d = 1.5. By x/d = 40, one street only is identifiable. Effective vorticity flux density indicates that, while the outer vortex nearer to the free stream interacts largely with the adjacent oppositely signed inner vortices located near the flow centreline, the inner vortex interacts with the cross-stream inner vortices as well as with adjacent outer vortices. As a result, vorticity associated with the inner vortex is annihilated quicker than that associated with the outer vortex, leading to the early disappearance of inner vortices and formation of a single street. The contribution of the coherent motion of various Reynolds-averaged quantities such as the momentum and heat fluxes has also been quantified and discussed in conjunction with the vortex structures of the flow and temperature fields.

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Section: The Velocity and Temperature Fluctuationssupporting

confidence: 82%

Section: Coherent Contribution To Reynolds Stresses and Heat Fluxessupporting

confidence: 79%

Section: Phase and Structural Averagingmentioning

confidence: 99%

See 1 more Smart Citation

The turbulent wake of two side-by-side circular cylinders

Zhou¹,

Zhang²,

Yiu³

2002

J. Fluid Mech.

172

134

View full text Add to dashboard Cite

show abstract

“…A phase relationship is evident between v and v R signals. As a matter of fact, the spectral coherence The phase-averaging method is similar to that used by Matsumura and Antonia 23 and Zhou et al 24 Briefly, the v-signals from the two X-wires were both digitally bandpass filtered with the center frequency set at the dominant vortex frequency, which was identified with f *ϭ0.069 for T 2 /dϭT 1 /dϭ1.5 and f *ϭ0.076 for T 2 /dϭ1.6 and T 1 /d ϭ1.5. Two phases of particular interest were identified on the filtered signal v f ͓Fig.…”

Section: B Phase-averaged Flow Patternmentioning

confidence: 99%

Effect of unequal cylinder spacing on vortex streets behind three side-by-side cylinders

Zhang

Zhou

2001

Physics of Fluids

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Strain-vorticity induced secondary motion in shallow flows Phys. Fluids 24, 023601 (2012) Developed quantum turbulence and its decay Phys. Fluids 24, 011301 (2012) A fully resolved numerical simulation of turbulent flow past one or several spherical particles Phys. Fluids 24, 013303 (2012) Decaying versus stationary turbulence in particle-laden isotropic turbulence: Turbulence modulation mechanism Phys. The turbulent near-wake of three side-by-side circular cylinders with equal or unequal spacing has been experimentally investigated using various techniques, including the hot wire, laser Doppler anemometer, and flow visualization. The work aims to understand the effect of unequal cylinder spacing on the vortex streets behind the three cylinders. When the cylinder center-to-center spacing is identical, i.e., T 1 /dϭT 2 /dϭ1.5, the flow is symmetric about the centerline, with one wide wake behind the central cylinder and one narrow wake on each side of the wide wake. The dominant frequency in the narrow wakes is about 5.4 times that in the wide wake. The observation is consistent with previous reports, thus lending credence to the present measurement. As T 2 /d is slightly increased to 1.6, a remarkable change occurs in the flow. A comparison is made between the cases of equally and unequally spaced cylinders in terms of the pressure around the cylinders, drag, lift, dominant frequencies, and vortex formation mechanisms. The flow topology ͑vortex patterns͒ and downstream evolution are also discussed in detail.

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“…The buoyancy effect due to the temperature difference was negligible and heat could be considered as a passive scalar (Matsumura & Antonia 1993). Measurements were carried out at x/d = 10 and 20.…”

Section: Methodsmentioning

confidence: 99%

Flow structure behind two staggered circular cylinders. Part 2. Heat and momentum transport

Zhou

2008

J. Fluid Mech.

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This work aims to study flow structures, heat and momentum transport in the wake of two staggered circular cylinders. In order to characterize heat transport in the flow, both cylinders were slightly heated so that heat generated could be treated as a passive scalar. The velocity and temperature fluctuations were simultaneously measured by traversing a three-wire (one cross-wire plus one cold wire) probe across the wake, along with a fixed cross-wire, which acted to provide a reference signal. Four distinct flow structures, i.e. two single-street modes (S-I and S-II) and two twin-street modes (T-I and T-II), are identified based on the phase-averaged vorticity contours, sectional streamlines, and their entrainment characteristics. Mode S-I is characterized by a vortex street approximately antisymmetric about the centreline. This mode is further divided into S-Ia and S-Ib, which differ greatly in the strength of vortices. The vortex street of Mode S-II is significantly asymmetric about the centreline, the strenth of vortices near the downstream cylinder exceeding by 50 % that on the other side. Mode T-I consists of two alternately arranged vortex streets; the downstream-cylindergenerated street is significantly stronger than that generated by the upstream cylinder. In contrast, Mode T-II displays two streets approximately antisymmetrical about the wake centreline. Free-stream fluid is almost equally entrained from either side into the wake in Modes S-Ia and T-II, but largely entrained from the downstream cylinder side in Modes S-II and T-I. The entrainment motion in Mode S-Ib is very weak owing to the very weak vortex strength. Vortices decay considerably more rapidly in the twin-street modes, under vigorous interactions between the streets, than in the single-street modes. This rapid decay is particularly evident for the inner vortices near the wake centreline in Modes T-II and T-I. Other than flow structures, heat and momentum transport characteristics are examined in detail. Their possible connection to the initial conditions is also discussed.

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Momentum and heat transport in the turbulent intermediate wake of a circular cylinder

Cited by 112 publications

References 9 publications

The turbulent wake of two side-by-side circular cylinders

The turbulent wake of two side-by-side circular cylinders

Effect of unequal cylinder spacing on vortex streets behind three side-by-side cylinders

Flow structure behind two staggered circular cylinders. Part 2. Heat and momentum transport

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