| Cavitation phenomena in mechanical heart valves: studied by using a physical impinging rod system. | |
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MedLine Citation:
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PMID: 20490686 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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When studying mechanical heart valve cavitation, a physical model allows direct flow field and pressure measurements that are difficult to perform with actual valves, as well as separate testing of water hammer and squeeze flow effects. Movable rods of 5 and 10 mm diameter impinged same-sized stationary rods to simulate squeeze flow. A 24 mm piston within a tube simulated water hammer. Adding a 5 mm stationary rod within the tube generated both effects simultaneously. Charged-coupled device (CCD) laser displacement sensors, strobe lighting technique, laser Doppler velocimetry (LDV), particle image velocimetry (PIV) and high fidelity piezoelectric pressure transducers measured impact velocities, cavitation images, squeeze flow velocities, vortices, and pressure changes at impact, respectively. The movable rods created cavitation at critical impact velocities of 1.6 and 1.2 m/s; squeeze flow velocities were 2.8 and 4.64 m/s. The isolated water hammer created cavitation at 1.3 m/s piston speed. The combined piston and stationary rod created cavitation at an impact speed of 0.9 m/s and squeeze flow of 3.2 m/s. These results show squeeze flow alone caused cavitation, notably at lower impact velocity as contact area increased. Water hammer alone also caused cavitation with faster displacement. Both effects together were additive. The pressure change at the vortex center was only 150 mmHg, which cannot generate the magnitude of pressure drop required for cavitation bubble formation. Cavitation occurred at 3-5 m/s squeeze flow, significantly different from the 14 m/s derived by Bernoulli's equation; the temporal acceleration of unsteady flow requires further study. |
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Authors:
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Chi-Wen Lo; Sheng-Fu Chen; Chi-Pei Li; Po-Chien Lu |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-05-20 |
Journal Detail:
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Title: Annals of biomedical engineering Volume: 38 ISSN: 1521-6047 ISO Abbreviation: Ann Biomed Eng Publication Date: 2010 Oct |
Date Detail:
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Created Date: 2010-09-16 Completed Date: 2010-12-30 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0361512 Medline TA: Ann Biomed Eng Country: United States |
Other Details:
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Languages: eng Pagination: 3162-72 Citation Subset: IM |
Affiliation:
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National Institute of Cancer Research, National Health Research Institutes, Tainan 70456, Taiwan. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Blood Flow Velocity / physiology Blood Viscosity / physiology* Heart Valves / physiology* Humans Models, Cardiovascular* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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