本文探討水流通過透水性筐網圓柱體，在離底床不同高度的流場特性。在平均來流速度（24.6 cm/sec）及平均水深（16 cm）之條件下，探討表面孔隙比及抬升高度，並使用三維下視型及二維側視型之聲波都普勒流速儀來量測流場之流速分佈。

經由實驗結果與相關理論驗證得知，水流通過筐網圓柱體後，流速將因筐網圓柱體後方的遮蔽效應而降低。另外，流入結構物內部而抵達柱體後方之穿越流具有穩定流場的特性，故於筐網圓柱體後方會形成一流況穩定之低流速區域，稱為「穩定低速區」。

This study uses the measurement of flow-field to analyze the characteristics of the fluid motion in the permeable porous cylinder at different height from the bottom , such as velocity distribution at centre section of cylinder . The relation between flow structure and physical parameters of porous cylinder at different height from the bottom , including void proportion and the heigh of uplift , is investigated .
According to the experiment results and the confirmation of related researches, flow velocity decreases after running through the porous cylinder because of the shelter effect. The “bleed flow,” which goes through inner structure and reaches the backward of porous cylinder, has the function to steady flow-field, so there is a steady and low-velocity area behind the porous cylinder, called “steady low-velocity area .”
On the same experimental condition (the averaged flow-velocity is 24.6 cm/sec, the averaged flow depth is 16 cm) , using of acoustic Doppler velocimeter to measure the fiow velocity distribution .

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