Three-dimensional flow structure in highly buoyant jet by scanning stereo PIV combined with POD analysis

Watanabe, Ryuta; Gono, T.; Yamagata, Takayuki; Fujisawa, Nobuyuki

doi:10.1016/j.ijheatfluidflow.2014.12.003

Cited by 37 publications

(8 citation statements)

References 29 publications

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“…Therefore, the Froude number of the vertical buoyant plume was Fr 0 = 4.23, and the Reynolds number was Re = 1670. The instantaneous structure of the vertical plume generated by the nozzle and its interaction with the stagnant surrounding air as well as the velocity distribution were steady which was the same as previous study [8]. Therefore, these conditions were sufficient for evaluating the 3D PIV measurement method.…”

Section: Experimental Setup Of 3d Piv Technique Using W-shaped Light supporting

confidence: 64%

Velocity Measurement by PIV Using W-Shaped Scanning Light Sheet

Funatani

Takeda²,

Toriyama³

2015

JFCMV

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This study proposes a three-dimensional (3D) particle image velocimetry (PIV) method using Wshaped light sheet and color PIV with a digital SLR camera. The uncertainty of the velocity measurement was also studied and it was acceptable. The spatial resolution of the z-direction has much room for improvement by increasing the number of cameras. When applied to the velocity distribution measurement of a thermal vertical buoyant plume, the proposed 3D PIV method is found to be very effective for studying thermal structures and well suited for measuring the airflow velocity field.

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Section: Experimental Setup Of 3d Piv Technique Using W-shaped Light supporting

confidence: 64%

Velocity Measurement by PIV Using W-Shaped Scanning Light Sheet

Funatani

Takeda²,

Toriyama³

2015

JFCMV

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“…According to the discrete dataset acquired by PIV, the snapshot POD method derived by Sirovich ( 1987 ) is applied to analyze the acquisition velocity field. The basic idea of snapshot POD is to obtain a set of optimal orthogonal eigenfunctions for a set of instantaneous velocity field (Berkooz et al 1993 ; Zhou and Hitt 2004 ; Watanabe et al 2015 ). In practical application, each instantaneous velocity field is regarded as a snapshot of the flow.…”

Section: Methodsmentioning

confidence: 99%

POD analysis of flow over a backward-facing step forced by right-angle-shaped plasma actuator

Wang

2016

SpringerPlus

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PurposeThis study aims to present flow control over the backward-facing step with specially designed right-angle-shaped plasma actuator and analyzed the influence of various scales of flow structures on the Reynolds stress through snapshot proper orthogonal decomposition (POD).Methods2D particle image velocimetry measurements were conducted on region (x/h = 0–2.25) and reattachment zone in the x–y plane over the backward-facing step at a Reynolds number of Reh = 27,766 (based on step height and free stream velocity . The separated shear layer was excited by specially designed right-angle-shaped plasma actuator under the normalized excitation frequency Sth ≈ 0.345 along the 45° direction. The spatial distribution of each Reynolds stress component was reconstructed using an increasing number of POD modes.ResultsThe POD analysis indicated that the flow dynamic downstream of the step was dominated by large-scale flow structures, which contributed to streamwise Reynolds stress and Reynolds shear stress. The intense Reynolds stress localized to a narrow strip within the shear layer was mainly affected by small-scale flow structures, which were responsible for the recovery of the Reynolds stress peak. With plasma excitation, a significant increase was obtained in the vertical Reynolds stress peak.ConclusionsUnder the dimensionless frequencies Sth ≈ 0.345 and which are based on the step height and momentum thickness, the effectiveness of the flow control forced by the plasma actuator along the 45° direction was ordinary. Only the vertical Reynolds stress was significantly affected.

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“…The analysis allows the evaluation of mean (0th mode) and fluctuating properties (1st mode, 2nd mode, ---) of the shadowgraph images, so that the result indicates the statistical properties of the cavitating jet. The details of the snapshot POD analysis have been described elsewhere [13], so that it is not repeated in this paper. Figure 2 shows time-series shadowgraph images taken by a CMOS camera operating at 6000 frames/sec.…”

Section: Snapshot Pod Analysismentioning

confidence: 99%

“…The snapshot POD is very useful for recognizing the coherent structure of turbulent flow [8] [9], channel flow [10], flow around a square cylinder [11], flame flickering [12] and highly buoyant jet [13]. By introducing the POD analysis, most energetic structure of the flow is extracted by decomposing the fluctuating properties of the fluid into the linear sum of orthogonal eigenfunctions of temporal and spatial correlations.…”

Section: Introductionmentioning

confidence: 99%

Shadowgraph Imaging of Cavitating Jet

Watanabe¹,

Kikuchi²,

Yamagata³

et al. 2015

JFCMV

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This paper deals with the statistical properties of unsteady structure of cavitating water-jet issuing into a stagnant fluid of water using the shadowgraph imaging combined with the proper orthogonal decomposition (POD) analysis. The experimental result indicates that the cavitating jet is composed of axisymmetric mode, while the periodic axial oscillation is found along the jet centerline. The reconstructed cavitation images show the presence of growing, shrinking and shedding motion in the cavitation cloud, which sustains a periodic behavior of the cavitating jet.

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Three-dimensional flow structure in highly buoyant jet by scanning stereo PIV combined with POD analysis

Cited by 37 publications

References 29 publications

Velocity Measurement by PIV Using W-Shaped Scanning Light Sheet

Velocity Measurement by PIV Using W-Shaped Scanning Light Sheet

POD analysis of flow over a backward-facing step forced by right-angle-shaped plasma actuator

Shadowgraph Imaging of Cavitating Jet

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