| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系 === 102 === The purpose of this thesis is to study the effects of concentration distribution
and velocity distribution to the behavior of debris flows. My governing equations is
integrated by conservation equations. The flow density in my research is not
constant and is vary with flow’s depth and sediment concentration. There are four
correction factors in the mass and momentum conservation due to the depth integration,
they are important to the simulation of debris flow. Building the relationship
between friction angle, bed slope, velocity, concentration and correction factors
is useful to the simulation of debris flow.
In the condition of steady state and uniform flows, we can use the stress and
pressure conservation to derive the velocity and concentration equations. There are
some factors to debris flow, such as friction angle, bed slope, diameter of sediment,
bed’s sediment concentration, density ratio and whether the bed is erodible or rigid.
After the research, we can obtain six point: (1) By depth integration, we have four
correction factors in mass and momentum conservation to describe debris flows; (2)
Under same friction angle, when the bed slope is larger, the concentration distribution
will be more uniform; (3) Under same friction angle, when the bed slope is
small, the flow field will separate into water layer and mixture layer. The proportion
of the water layer will increase while the bed slope decrease; (4) No matter the
friction angle and bed slope are, the mixture layer’s velocity distribution are very
similar and linear; (5) On the rigid bed, the bed’s sediment concentration will influence
the distribution of concentration and velocity; (6) Bed’s condition will influence
the distribution of velocity and sediment concentration. Under same friction
angle and bed’s slope, the concentration and velocity profile are different apparently
between erodible and rigid bed.
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