| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系 === 84 === In this paper we use the strain gages at the "crest",
"lee side" and "trough" in the ripple model . So as to
measuring shear stress in oscillatory water tunnel. In
addition we employ the "LDV" system to measure the velocity
field near the ripple. 1.For measuring shear stress: Indicating
that the shear stress at "crest" is larger than at "lee side" .
And the one at "lee side" are larger than at "trohgh". We find
the flow in this study was rough turbulent flow by using
Vongvisessomjai's regime function. And we using Jonsson's
definition of friction factor "fw", and the form roughness "Ks"
can be calculated from Swart's formula. Finally we using "fw"
and "Ks" to do dimensional analysis and gain fitting curve for
each other. 2.For measuring velocity: We using the "LDV"
system to measure velocity field. We find the condition-"over
shooting" at crest. At lee side the flow is confusion, then the
velocity profile nonsmoothly. And the velocity profile at the
trough is smooth. Finally we get the eddy viscosity "ε" by
calculating with measuring shear stress and velocity field
profile. In our experiment condition, the eddy viscosity "ε"
value approximately ranges from 0.0000392 to 0.000422.
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