X-ray-Based Flow Visualization and Measurement SEEGER, AXEL; AFFELD, KLAUS; GOUBERGRITS, LEONID ...
Annals of the New York Academy of Sciences,
10/2002, Letnik:
972, Številka:
1
Journal Article
Recenzirano
: Information concerning continuous or discreet phase flow in multiphase systems is desired for various practical and analytical applications. The potential of X‐ray‐based flow visualization and ...measurement of multiphase flow is demonstrated here by two non‐intrusive methods: (1) Measurement of the three‐dimensional (3D) velocity field of the continuous liquid phase in a bubble column by X‐ray‐based particle tracking velocimetry (PTV) of seeded particles. (2) Liquid flow visualization in a bubble column by injecting an X‐ray absorbing liquid into the bubble column. X‐rays have the advantage that they are not affected by the various refraction indices of the multiphase system and penetrate the multiphase flow in undistorted straight lines. Hence, in contrast to optical methods, both of these X‐ray‐based methods are independent of the void fraction and are applicable to opaque liquids.
Atherosclerotic ailments play a major role in industrial societies. Atherosclerotic disease causes stenotic narrowing of the arterial vessel system. These narrow passages can be widened with balloon ...angioplasty and stents are introduced to keep the passage open. In this study, stents designed for the aorto-iliac bifurcation are considered. Most of these stents used in peripheral arteries are self-expanding stents made from Nitinol, a thermo-reactive alloy. The insertion is done under radiographic control. However, the delicate metallic structure of the stent usually casts only a weak radiographic shadow and thus is difficult to detect. A stent with an innovative radio opaque tantalum marker (Luminexx, C.R. BARD--Angiomed, Karlsruhe), overcomes this problem. However, the markers extend into the blood flow and the question arises whether the markers may cause the generation of thrombi. In a model study in an enlarged model of the aorto-iliac bifurcation with an inserted stent the flow was visualized. The enlarged scale permits the observation and video recording of the flow in great detail. The Reynolds similarity is kept. A subsequent analysis of the flow in the vicinity of the markers shows a short residence time. These results indicate that the additional markers do not increase the risk of thrombus generation.
This chapter describes the development of a new time resolved 3D PIV technique for near wall flow field measurements. This measurement technique, called wall-PIV, is based on Beer-Lambert’s law. It ...substitutes the classical PIV laser sheet by a diffuse, monochromatic full-field illumination that is limited to the near wall region by an absorbing molecular dye in the fluid. Aimed range of applications is the investigation of flow fields next to one- or two dimensionally curved, possibly flexing surfaces. The three dimensional three component flow estimation uses a new optical flow algorithm, based on particle trajectories. Results of the measurement technique’s application on a displacement pediatric blood pump are presented.
Intravital microscopy (IVM) is a well-established imaging technique for real-time monitoring of microscale lung tissue dynamics. Although accepted as a gold standard in respiratory research, its ...characteristic image features are scarcely understood, especially when trying to determine the actual position of alveolar walls. To allow correct interpretation of these images with respect to the true geometry of the lung parenchyma, we analyzed IVM data of alveoli in a mouse model in comparison with simultaneously acquired optical coherence tomography images. Several IVM characteristics, such as double ring structures or disappearing alveoli in regions of liquid filling, could be identified and related to the position of alveoli relative to each other. Utilizing a ray tracing approach based on an idealized geometry of the mouse lung parenchyma, two major reflection processes could be attributed to the IVM image formation: partial reflection and total internal reflection between adjacent alveoli. Considering the origin of the reflexes, a model was developed to determine the true position of alveolar walls within IVM images. These results allow thorough understanding of IVM data and may serve as a basis for the correction of alveolar sizes for more accurate quantitative analysis within future studies of lung tissue dynamics.
Provider: - Institution: - Data provided by Europeana Collections- Bibliogr. przy pracach- Bibliogr. przy pracach- All metadata published by Europeana are available free of restriction under the ...Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Bibliogr. przy pracach- Bibliogr. przy pracach- All metadata published by Europeana are available free of restriction under the ...Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
