| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1991: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1990: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
In this study, we investigate experimentally about three subjects, I. hydraulic jump and wave flow on large scale roughness(strip roughness and block roughness), 2. the growth of the internal boundary layer in the flow at abrupt change of bed roughness, 3. the effect of the channel width on the classical hydraulic jump.
On 1. subject, the follows were obtained.
(1)For a jump formed on large scale roughness, sequent depth, and the length of the surface roller of the jump is clearly reduced. The reduction in the relative length of the surface roller(Lr/h1)ranges from 30% to 40%. (2)The occurrence conditions and the characteristics of surface profiles for the wave flow on large scale-roughness agree almost with the wave flow at abrupt drops. (3)The decay of maximum velocity is more rapid, the growth of the boundary layer thickness is faster when compared with the corresponding smooth bed jump.
On 2. subject, (1)the velocity and turbulent intensity profiles of flow downstren of abrupt change from smooth bed to rough beds which are composed of glass beds were discussed. (2)The internal boundary layer thickness can be derived from the turbulent intensity profiles. (3)The development of the internal boundary layer(delta)may be given as delta = a・X^b, (b<similar or equal>0.7).
On 3. subject, the influence of scale effect and aspect ratio for hydraulic jump is discussed from sequent depth, water surface fluctuations, energy loss in the jump, and velocity distributions at the end of the jump.
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