本研究以定床實驗渠床量測流場的方式，分析透水性筐網圓柱群周圍及其前、後方流場之特性，包括水深平均速度場分佈及流場擾動程度等。
在本試驗條件下(平均來流速度23.2cm/sec；平均水深16cm)，探討筐網群對整體流場之影響，主要使用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，隨筐網數量的增加，水流通過筐網圓柱群後之縱向流速u及橫向流速v皆有增加之趨勢且隨著架設之角度產生一導流作用，但也因筐網支數之增加，導致筐網周圍流況處於最為不穩定的區域。另外，水流流入筐網圓柱體內部而抵達圓柱體後方之穿越流具有穩定流場的特性，加上筐網群內側下游因前方圓柱群所形成的遮蔽效應而形成低流速、低紊動之區域，此區即稱為「穩定低速區」。

This study uses the measurement of flow-field to analyze the characteristics of the fluid around and behind permeable porous cylinder groups, such as depth-averaged velocity distribution and disturbance level.
On the same experimental condition (the averaged flow-velocity is 23.2 cm/sec, the averaged flow depth is 16 cm), discusses the porous cylinder groups to influence of the overall flow field,using of acoustic Doppler velocimeter to measure the fiow velocity distribution .
According to the experiment results and the confirmation of related researches, flow velocity decreases after running through the porous cylinder groups because of the shelter effect and along with erects the angle to form a diversion 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.”
The steady low-velocity area develops behind porous cylinder groups, but the both sides of cylinder are turbulent exceeding-velocity zones. To take advantage of this velocity distribution type, using porous cylinder as flow diversion and pier-scour countermeasure could get an excellent result.

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