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    Please use this identifier to cite or link to this item: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/35624

    Title: 具截面變化之微流道流場模擬
    Other Titles: Numerical simulation of microchannel flows with variable cross section
    Authors: 高耿偉;Gao, Geng-wei
    Contributors: 淡江大學航空太空工程學系碩士班
    陳慶祥;Chen, Ching-shung
    Keywords: 微流道;截面變化;邊界層方程式;質流率;渦漩;可壓縮流;microchannel;boundary-layer equation;compressible flow;variable cross section;mass flow rate;vortex
    Date: 2007
    Issue Date: 2010-01-11 06:53:02 (UTC+8)
    Abstract: 在現今微流道流場研究下幾何結構大都是等直徑管道,在本研究中除了使用邊界層方程式計算圓形管可壓縮內流場來縮減運算時間外,並且藉由管道截面變化使流場產生渦漩,加以探討在可滑動壁面與不可滑動壁面渦漩與質流率的比較,以及藉由fluent來驗證邊界層方程式的準確性。
    In recent years most studies of microchannel flows focus on channels with constant cross-section. This study uses the boundary layer equations to calculate compressible microchannel flows with variable cross-section. The commercial software package, FLUENT was used to verify the present numerical procedure. Reverse flows were generated downstream of the expansions. The effects of slip conditions on the friction and the reverse flow were discussed.
    In this study we first demonstrate how to use the boundary layer method to successfully simulate reverse flows inside the channel. We investigated two variable cross-sections, one is the hyperbolic wavy channel (or nozzle channel) and the other is the sudden expansion channel. In order to stabilize the reverse flow, the implicit scheme was used to calculate the flow in the variable cross-section and the explicit scheme was used for the other part of the flow. The continuity equation was used to obtain the radial velocity, and the coupled scheme must be used in simulating sudden expansion flows.
    The results show that the slip boundary conditions produce less pressure losses, faster axial velocities, longer recirculation zones, and longer reattachment points when compared with the corresponding flows with the nonslip boundary conditions. The length of the recirculation zones is determined by Reynolds number and is independent of the types of working fluids utilized.
    Due to the assumptions and modifications employed in the present method in simulating the reverse flows, the recirculation zones predicted might not be very accurate. But the results are still acceptable for engineering purposes. Furthermore, the major advantage of the present numerical procedure is its fast speed due to the parabolic character of the governing equations. It was found that the present boundary layer method is two to three orders of magnitude faster than the full Navier-Stokes simulation, yet it provides acceptable accuracy.
    Appears in Collections:[航空太空工程學系暨研究所] 學位論文

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