scholarly journals STUDY ON TURBURENCE STRUCTURES IN PARTLY VEGETATED OPEN-CHANNEL FLOWS WITH A PARTICLE-IMAGE VELOCIMETRY (PIV)

1998 ◽  
Vol 42 ◽  
pp. 409-414
Author(s):  
Iehisa NEZU ◽  
Kouki ONITSUKA ◽  
Hideki JOHMEN ◽  
Yuki SAGARA
Keyword(s):  
Particle Image Velocimetry ◽  
Open Channel ◽  
Particle Image ◽  
Channel Flows ◽  
Open Channel Flows ◽  
Image Velocimetry

scholarly journals Investigation of Coherent Vortices in Partly Vegetated Open-channel Flows with a Particle-Image Velocimetry

1998 ◽  
Vol 1 ◽  
pp. 719-728
Author(s):  
Iehisa NEZU ◽  
Kouki ONITSUKA ◽  
Hideki JOHMEN ◽  
Yuki SAGARA ◽  
Kazuya IKETANI
Keyword(s):  
Particle Image Velocimetry ◽  
Open Channel ◽  
Particle Image ◽  
Channel Flows ◽  
Open Channel Flows ◽  
Image Velocimetry ◽  
Coherent Vortices

PIV Analysis of the Flow Pattern Around an Ablation Catheter to Observe the Flow Effect on the Electrode

2013 ◽  
Author(s):  
Kaihong Yu ◽  
Tetsui Yamashita ◽  
Shigeaki Shingyochi ◽  
Kazuo Matsumoto ◽  
Makoto Ohta
Keyword(s):  
Blood Flow ◽  
Particle Image Velocimetry ◽  
Catheter Ablation ◽  
Flow Pattern ◽  
Open Channel ◽  
Particle Image ◽  
Circulation System ◽  
Convection Flow ◽  
Image Velocimetry ◽  
Catheter Tip

Radiofrequency (RF) catheter ablation is a highly effective treatment for many cardiac arrhythmias, especially for tachyarrhythmia. RF energy is introduced through the catheter onto the endocardial surface to destroy the abnormal heart tissue causing the heart rhythm disorder. Many parameters relate to myocardial temperature, such as RF power, tissue contact, and blood flow. Blood flow is an important factor that has a cooling effect on myocardium and affects the final lesion size. Many previous studies have shown that under temperature control, lesion sizes are larger and tissue temperatures rise faster with a high flow rate. If the flow causes a decrease in the temperature of the catheter tip, the generator will increase the power output to maintain the tip at a constant temperature. However, few studies of RF catheter ablation have investigated how ablation affects blood flow. Observation of the flow pattern around the catheter can help to determine the mechanism of the flow effects on the temperature of the catheter tip. The purpose of this study is to observe the flow pattern during ablation using an in-vitro circulation system developed for Particle Image Velocimetry (PIV). We developed an open-channel circulation system to simulate blood flow. The mold for the open-channel was built with acrylic boards for transparency. The working fluid was 0.9% saline, which was used at room temperature (20°C). Instead of animal myocardium, we used a poly (vinyl alcohol) hydrogel (PVA-H), which has mechanical characteristics that approximate those of biological soft tissue, and contact with the PVA-H surface by the catheter is similar to that with myocardium. A 7 Fr catheter with a 4-mm ablation electrode tip was set perpendicular to the PVA-H surface, and the contact weight between the electrode of the catheter and the PVA-H surface was 2.2 gf. To measure the temperature profile in the PVA-H, a K-type thermocouple with the diameter of 0.5 mm was placed at the depth of 2 mm from the surface. The thermocouple tip was always placed on the catheter axis. The flow pattern at the location where the catheter was held was observed by a high speed camera, and the resulting images were analyzed by particle image velocimetry (PIV). The results showed that in the absence of applied flow, convection flow from the electrode is observed in the areas around the catheter. However, under a 1.6 L/min flow rate, convection flow disappears. In conclusion, blood flow could decrease the catheter tip temperature, and the influence of ablation in the flow around the catheter disappeared.

scholarly journals Reconstructing Depth‐Averaged Open‐Channel Flows Using Image Velocimetry and Photogrammetry

2018 ◽  
Vol 54 (6) ◽  
pp. 4164-4179 ◽  
Author(s):  
Guillaume Piton ◽  
Alain Recking ◽  
Jérôme Le Coz ◽  
Hervé Bellot ◽  
Alexandre Hauet ◽  
...  
Keyword(s):  
Open Channel ◽  
Channel Flows ◽  
Open Channel Flows ◽  
Image Velocimetry

scholarly journals A new method for extracting spanwise vortex from 2D particle image velocimetry data in open-channel flow

2020 ◽  
Vol 68 (3) ◽  
pp. 242-248
Author(s):  
Peng Zhang ◽  
Shengfa Yang ◽  
Jiang Hu ◽  
Wenjie Li ◽  
Xuhui Fu ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Channel Flow ◽  
Vortex Structure ◽  
Open Channel ◽  
Particle Image ◽  
Open Channel Flow ◽  
New Method ◽  
Two Dimensional ◽  
Image Velocimetry ◽  
Spanwise Vortex

AbstractThe two-dimensional particle image velocimetry (PIV) data are inevitably contaminated by noise due to various imperfections in instrumentation or algorithm, based on which the well-established vortex identification methods often yield noise or incomplete vortex structure with a jagged boundary. To make up this deficiency, a novel method was proposed in this paper and the efficiency of the new method was demonstrated by its applications in extracting the two-dimensional spanwise vortex structures from 2D PIV data in open-channel flows. The new method takes up a single vortex structure by combining model matching and vorticity filtering, and successfully locates the vortex core and draws a streamlined vortex boundary. The new method shows promise as being more effective than commonly used schemes in open-channel flow applications.

Experimental Study on the Flow Around a Moving Cylinder

2013 ◽  
Author(s):  
Yangyang Gao ◽  
Danielle S. Tan ◽  
Baofeng Zhang ◽  
Soon Keat Tan
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Particle Image Velocimetry ◽  
Horizontal Plane ◽  
Open Channel ◽  
Particle Image ◽  
Ball Bearing ◽  
Flow Behavior ◽  
Moving Cylinder ◽  
Image Velocimetry

An experimental investigation of flow behavior behind a moving circular cylinder was carried out in an open channel. The cylinder was mounted on a platform and extended to submerge in the water. The platform was rested on two ball-bearing-filled tracks which were designed to reduce the friction between the platform and the tracks. The cylinder was maintained perpendicular to the platform. The platform was free to move in a horizontal plane. The flow fields behind the suspended cylinder were captured using the technique of Particle Image Velocimetry (PIV) and the trajectory of the cylinder was captured using a camera operated in video mode (60 frames per second). Instantaneous flow patterns and orbital responses of the moving cylinder were analyzed and the findings were presented herein.

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