| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系 === 84 === The present paper is aimed to develop a mathmatical model
for simulatingunsteady flow and bed variations in alluvial
rivers. The numerical model is developed using an explicit
finite-difference scheme on governing equationsof alluvial
rivers. Apeicewise uncoupled method is utilized to improved the
efficient of compution. Processes during weting and drying can
be performedfor simulating unsteady flow. For the computation of
bed evolution, With thehelp of diffusive scheme (de Vries
1973),suspended load can be obtained bysolving suspended
sediment convection-diffusion equation under unblanced sediment
transportation condition. A set of experiment data on
channel-contraction is used to test the ability of this model.
Comparisons with measured data show the same tendencebetween the
computed and experimential data. Furthermore, two different bed-
load formulas are adopted that the bed-load formula''s influence
is upon amount The applicability of this model can be
performed by simulating the bed evolutions of Tseng-Wen River
during flood course. The calculated consequencesin icate that
the main-channel will occur intense erosion and form a larger
sharp in earlier stages of swell. Nevertheless, the great
majority of floodplanes will silt. Comparisons of the suspended
sediment concentractional betweenthe main-channel and flood
plans demonstrate that the concentractional of main-channel was
more heavy and even than flood planes. The computational results
show that the capability of the model insimulating unsteady flow
and bed evol-utions in nature rivers has been verified.
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