| Summary: | 博士 === 國立臺灣大學 === 環境工程研究所 === 84 === The contents of this thesis have three major parts: (1) the
analysis of dispersion properties inherent in numerical
particle trajectory models, (2) simulations of developing
turbulent flow in the inlet region of a pipe and the
evaluations of inflow turbulence effects on the development of
the turbulent flow, and (3) deposition mechanisms and
concentration distribution of aerosol particles in the inlet
region of a pipe. For the first, nine particle trajectory
models were investigated. Based on the mechanisms with each
model, the dispersion properties inherent in each models were
derived in homogeneous turbulence. How to choice the time
interval associated with each model so as to confirm some
theoretical results were suggested. In addition, the
influences of relaxation time and initial velocity of
particle on the particle dispersion were examined. In
simulating the developing turbulent flow, we first
evaluated the performances of six versions of turbulence
models. The results revealed that most models have excellent
simulations of the mean velocity; however some discrepancies
were found in predicting the turbulent kinetic energy and
Reynolds stress in the inlet region. The variations of inflow
turbulence had little influence to the develop of boundary
layers. In investigating the deposition mechanisms, the
results shown that turbulence and lift force are the
most important mechanisms to arise the deposition of
aerosol particle in the inlet region. The magnitude of
inflow turbulent intensity influences the particle depositions
deeply; however the turbulent length and time scale have
little influence on the particle deposition. And, the
turbulent boundary and the turbulence in the free stream
are reverent to the distributions of particle concentrations
in the inlet region.
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