Uniformity Of Flow Velocity Research Articles

516 ポンプレスECMO用人工肺の開発に関する研究(OS5-(3)オーガナイズドセッション《ライフサポートにおける工学技術》)

We have developed oxygenetor for pumpless Extracorporeal Membrane Oxygenation (ECMO) system. It is required low pressure drop, blood priming volume and gas exchange performance in pumpless ECMO. In this study, we performed analysis of oxygenetor using computational fluid dynamics (CFD) for increase in performance. In addition, oxygenetor was fabricated based on the result of CFD. In the CFD, it was calculated uniformity of flow velocity in fiber bundle, low blood pressure and low riming volume. O_2 was fully added to oxygenator, on the other hand, CO_2 removal was difficult in in vitro evaluation. The value of pressure drop was not constant was by nonuniformly of flow velocity. In conclusion, this result indicates that uniformity of flow velocity was depended on gas exchange performance and pressure drop.

C103 回流水槽における模型船の造る浅水波の可視化

It is important to consider shallow water effect for design of ships, because there are several differences when the ship is sailing in shallow water and in deep water. Many studies have been done, however few experiments have been done because a special device is necessary to simulate the shallow water condition and visualize shallow water waves. In this study, a device for shallow water effect in a circulating water channel is developed. Experiments are carried out to study the performance of the device for shallow water effect. For these purposes, relationship between rotation of impeller and flow velocity and uniformity of flow velocity in the device should be investigated. Experimental visualizations of the shallow water wave using this device are carried out, and crest angles of the diverging wave are measured and discussed.

STUDY ON EVALUATION OF ARTIFICIAL IMPLANTABLE LUNG DESIGN

In a previous study, we constructed an automatic optimization system applying Multi Objective Genetic Algorithm (MOGA) and Computational Fluid Dynamics (CFD), and developed an Artificial Implantable Lung (AIL) possessing antithrombogenicity and high gas exchange performance based on fluid dynamics. In the result of in vitro experiment, this system was shown to be useful as a design and development support system for high-performance artificial organs. In the currently study, we evaluated the AIL design for further long-term use using the designs optimized by the automatic optimization system. The velocity and pressure distribution was calculated by CFD software STAR-CD (CD-adapco, JAPAN). Two AIL designs (original design: OD and optimum design: OPT) were used in order to evaluate AIL design. OD was characterized by arc extrusion shape and symmetry at the inflow and outflow parts. OPT had taper shape and asymmetry at the inflow and outflow parts. In OPT, the uniformity of flow velocity to the fiber bundle was decreased by 75.1% and the gas exchange performance was increased by 29.4% when compared with OD in the previous optimization. In OPT, the flow velocity attenuated with the taper wall in the inflow part. High pressure was caused in the taper wall and the pressure was decreased by almost constant value. In conclusion, it was considered that the fluid kinetic energy was converted into the pressure energy by the taper wall in the inflow part, and the fluid was uniformly diffused to the fiber bundle by the pressure.

Flow velocity profile of the pulmonary artery measured by the continuous cardiac output monitoring catheter

The KATS catheter (continuous arterial thermodeprivation system catheter) measures the blood flow velocity of the pulmonary artery (PA) by thermodeprivation which enables continuous determination of cardiac output. The accuracy of this system may depend on the degree of uniformity of flow velocity in the PA, because small movements of the catheter within the PA are inevitable with a beating heart. We evaluated the flow velocity profile of the PA in seven anaesthetized open-chest dogs to assess these potential errors. A custom-made stiff catheter, at the tip of which was incorporated the flow velocity sensor of the KATS catheter, was used to penetrate the main PA in the short axis direction (perpendicular to flow direction) or the long axis direction (along flow direction). The stiff catheter was moved in increments of 2.5 mm, and flow velocity was recorded. The wall-to-wall distance of the PA along each direction was divided into five sections (S1 to S5 for the short axis, and L1 to L5 for the long axis). Flow velocity data for each section were averaged and presented as relative values against the control mid-point velocity. Along the short axis, flow velocity was 0.41 +/- 0.20 (SD), 1.00 +/- 0.10, 1.03 +/- 0.10, 1.08 +/- 0.13 and 0.49 +/- 0.26 from S1 to S5, i.e., lower in S1 and S5 which were close to the vascular walls (P < 0.05) but uniform in other areas. Along the long axis, flow velocity was 0.28 +/- 0.28, 0.88 +/- 0.09, 0.94 +/- 0.08, 1.06 +/- 0.25 and 1.28 +/- 0.50 from L1 to L5.(ABSTRACT TRUNCATED AT 250 WORDS)