TANISHITA Kazuo Keio University, System Design Engineering, Professor, 理工学部, 教授 (10101776)
NAKANO Kazuo Shibaura Institute of Technology, Mechanical Control Systems, Professor, システム工学部, 教授 (30016761)
The vascular disease such as the atherosclerosis is apt to initiate around the arterial branch. Also, the fluid mechanical damage such as the erosion and the corrosion frequently occurs at the edge corner of the T branch which is one of the most important fluid elements. Therefore, the vascular disease and the fluid mechanical damage are associated with the fluid mechanical interaction such as the wall shear stress which affects the boundary wall between tube wall and fluid flow. In the present project, the establishment of the direct measurement method of wall shear stress and the development for shear stress sensor has been tried using the electrochemical method. Up to now, the wall shear stress can only estimated through the velocity profile or the dynamic pressure near boundary wall. The electrochemical method, in which the redox system comprises the electrolyte and the test platinum cathode, is the only direct measurement technique of wall shear stress.
First, the frequency characteristics is investigated in laminar sinusoidal pulsating flow which simulates the blood flow. The frequency response is valid for the non dimensional frequency less than 10. Second, in turbulent flow the present method is valid for the Reynolds number less than 5000. Furthermore, the present method has been applied several flow situations, i.e., the right angle branch simulating the arterial bifurcation, the cerebral artery model, the respiratory asymmetrical bifurcation, and T branch as the pipeline element. Consequently, the specification of wall shear stress sensor such as the diameter of electrode, the adhesive agent, the electrolytic solution, and the annealing method has been established.