2006 Fiscal Year Final Research Report Summary
Dynamical Management of Boundary Layer with Manipulating Hierarchy Structure of Turbulent Eddy
| Project/Area Number |
17560152
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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 |
Fluid engineering
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| Research Institution | Yamaguchi University |
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Principal Investigator |
MOCHIZUKI Shinsuke Yamaguchi University, Faculty of Engineering, Professor, 大学院理工学研究科, 教授 (70190957)
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| Co-Investigator(Kenkyū-buntansha) |
OSAKA Hideo Yamaguchi University, Faculty of Engineering, Professor, 教授 (90024611)
KAMEDA Takatsugu Yamaguchi University, Faculty of Engineering, Assistant prtfessor, 講師 (70304491)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Turbulence / Boundary Layer / Management / Self-similarity / Streamwise Vortical Structure |
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| Research Abstract |
An experimental study has been made on management of wall bounded shear flows by introducing a pair of streamwise vortex, with temporal variation in diameter and strength, into the wall layer. The focus was placed to see what effects of the management on the hierarchical structure of turbulent eddy emerge in the self-similarity in the wall layer. Experimental work was made in three kinds of the wall turbulence, namely, boundary layer, two-dimensional channel flow, and turbulent wall jet. Concluding remarks obtained from the experimental study are summarized as follows.
1. Under a adverse pressure gradient, hierarchical structure and existence of the wall law is confirmed in the wall layer of boundary layer.
2. A pair of streamwise vortex with temporal variation in diameter and strength was introduced into the inner layer of plane turbulent wall jet. It is seen that the management is effective for use of practical application; streamwise momentum flux is increased and transported toward t
… More
he wall.
3. The wall bounded shear flow managed by the streamwise vortex with temporal variation in diameter and strength recovers faster than the streamwise vortex without the temporal variation. It is understood that the streamwise vortex with temporal variation is resemble to turbulent eddies in undisturbed wall layer.
4. Detailed study on the effect of periodic velocity components in dynamics was performed with phase averaging technique and triple decomposition of instantaneous fluctuating velocity components. Evaluation of production terms involved in Reynolds shear stress and turbulent energy equations shows considerable contribution of periodic component to momentum and energy balance.
5. Investigation of energy transport with the triple decomposition suggests validity of eddy viscosity model considering non-local effect due to large scale motion.
The experimental study shows that, with management of streamwise vortex considering the hierarchical structure, the shear layer recovers faster to similarity profile and enhances both entrainment of the free stream fluid and momentum transport toward the wall. Less
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Research Products
(16 results)
