1998 Fiscal Year Final Research Report Summary
Study on actively deforming propulsor which adapts its circumstance
| Project/Area Number |
09651015
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
船舶工学
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
DOI Yasuaki Engineering, Associate Professor, 工学部, 助教授 (10134454)
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| Co-Investigator(Kenkyū-buntansha) |
NINOMIYA Sinji Hiroshima International University Health Sciences, Associate Professor, 保健医療学部, 助教授 (60237774)
HIGO Yasushi Engineering, Associate Professor, 工学部, 助教授 (20156582)
MORI Kazu-hiro Engineering, Professor, 工学部, 教授 (90011171)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Thrust / Peristaltic / waving motion / Low Reynolds Number |
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| Research Abstract |
Unsteady viscous flow fields around a peristaltic motion of body and a wavy oscillating plate in highly viscous fluid are studied. The main objective is to study the abilities of peristaltic or a wavy oscillating motion to produce thrust in highly viscous fluid.
Firstly, the measurement of force is carried out to find out the possibility of obtaining propulsive force by peristaltic motion. It is proved that a propulsion force can be generated by peristaltic motion which can be applied as a propulsor in highly viscous fluid. For further studies, numerical works are also performed to investigate the mechanism of peristaltic motion. A contractive and dilative motion of body is also studied with trochoidal motion as well as with sin wave motion It is found that the propulsive force can be more easily obtained by a trochoidal motion in extremely high viscous flow. The numerical scheme can be a useful tool for such investigation, because it is hard to be studied precisely only by experiments.
The flow around a oscillating plate is also simulated by solving the full 3D unsteady Navier-Stokes equations. Through the computation, it is found that the pressure is acting as thrusting force while the frictional force is acting as resistance during the oscillation. Dependency of the wave number and phase velocity on the thrust and propulsive efficiency is investigated. In the case of inviscid fluid, the propulsive efficiency becomes largest when the phase velocity equals to the oncoming velocity. However in the case of viscous fluid, the maximum efficiency is given when the phase velocity is higher than the oncoming velocity. As the Reynolds number becomes lower, the portion of the frictional resistance is getting large and the propulsive efficiency is getting small. Effective way to get the thrusting force at low Reynolds number is discussed through the simulation.
The present study is expected to be applied for the development of a propulsor for micro-hydro-machine.
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