A Critical Analysis of the Particle Image Velocimetry Technique as Applied to Water Waves

2002 ◽

Vol 2 (5-6) ◽

pp. 47-55

Author(s):

N.-S. Park ◽

H. Park

Keyword(s):

Particle Image Velocimetry ◽

Particle Image ◽

Velocity Fields ◽

Local Velocity ◽

Mixing Condition ◽

Particle Image Velocimetry Technique ◽

Velocity Gradients ◽

Image Velocimetry ◽

Current Design ◽

G Value

Recognizing the significance of factual velocity fields in a rapid mixer, this study focuses on analyzing local velocity gradients in various mixer geometries with particle image velocimetry (PIV) and comparing the results of the analysis with the conventional G-value, for reviewing the roles of G-value in the current design and operation practices. The results of this study clearly show that many arguments and doubts are possible about the scientific correctness of G-value, and its current use. This is because the G-value attempts to represent the turbulent and complicated factual velocity field in a jar. Also, the results suggest that it is still a good index for representing some aspects of mixing condition, at least, mixing intensity. However, it cannot represent the distribution of velocity gradients in a jar, which is an important factor for mixing. This study as a result suggests developing another index for representing the distribution to be used with the G-value.

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A New Particle Image Velocimetry Technique for Turbomachinery Applications

Journal of Turbomachinery ◽

10.1115/1.4033672 ◽

2016 ◽

Vol 138 (12) ◽

Cited By ~ 4

Author(s):

Sayantan Bhattacharya ◽

Reid A. Berdanier ◽

Pavlos P. Vlachos ◽

Nicole L. Key

Keyword(s):

Particle Image Velocimetry ◽

Particle Image ◽

Laser Sheet ◽

Measurement Techniques ◽

Leakage Flow ◽

Tip Leakage Flow ◽

Particle Image Velocimetry Technique ◽

Optical Access ◽

Tip Leakage ◽

Image Velocimetry

Nonintrusive measurement techniques such as particle image velocimetry (PIV) are growing in both capability and utility for turbomachinery applications. However, the restrictive optical access afforded by multistage research compressors typically requires the use of a periscope probe to introduce the laser sheet for measurements in a rotor passage. This paper demonstrates the capability to perform three-dimensional PIV in a multistage compressor without the need for intrusive optical probes and requiring only line-of-sight optical access. The results collected from the embedded second stage of a three-stage axial compressor highlight the rotor tip leakage flow, and PIV measurements are qualitatively compared with high-frequency response piezoresistive pressure measurements to assess the tip leakage flow identification.

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Abstract 14952: Volumetric Echocardiographic Particle Image Velocimetry (V-Echo-PIV)

Circulation ◽

10.1161/circ.130.suppl_2.14952 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Ahmad Falahatpisheh ◽

Arash Kheradvar

Keyword(s):

Particle Image Velocimetry ◽

Particle Image ◽

Contrast Echocardiography ◽

Ultrasound Contrast Agent ◽

Three Dimensions ◽

Small Scale ◽

High Temporal Resolution ◽

Two Dimensional ◽

Particle Image Velocimetry Technique ◽

Image Velocimetry

Introduction: The two-dimensional (2D) echocardiographic particle image velocimetry technique that was introduced in 2010 received much attention in clinical cardiology. Cardiac flow visualization based on contrast echocardiography results in images with high temporal resolution that are obtainable at relatively low cost. This makes it an ideal diagnostic and follow-up tool for routine clinical use. However, cardiac flow in a cardiac cycle is multidirectional with a tendency to spin in three dimensions rather than two-dimensional curl. Here, for the first time, we introduce a volumetric echocardiographic particle image velocimetry technique that robustly acquires the flow in three spatial dimensions and in time: Volumetric Echocardiographic Particle Image Velocimetry (V-Echo-PIV). Methods: V-Echo-PIV technique utilizes matrix array 3D ultrasound probes to capture the flow seeded with an ultrasound contrast agent (Definity). For this feasibility study, we used a pulse duplicator with a silicone ventricular sac along with bioprosthetic heart valves at the inlet and outlet. GE Vivid E9 system with an Active Matrix 4D Volume Phased Array probe at 30 Hz was used to capture the flow data (Figure 1). Results: The 3D particle field was obtained with excellent spatial resolution without significant noise (Figure 1). 3D velocity field was successfully captured for multiple cardiac cycles. Flow features are shown in Figure 2 where the velocity vectors in two selected slices and some streamlines in 3D space are depicted. Conclusions: We report successful completion of the feasibility studies for volumetric echocardiographic PIV in an LV phantom. The small-scale features of flow in the LV phantom were revealed by this technique. Validation and human studies are currently in progress.

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