摘要 生物反應器可以提供一個體外的細胞培養生長環境，以觀察反應器所提供的機械性刺激對細胞的影響。而在各種生物反應器中，圓錐平板型可在同一裝置中提供層流至紊流型式的剪切力環境，因此可用來模擬血液流動對血管內皮細胞造成的流體剪切力，研究剪切力對血管內皮細胞生長的影響。 本篇研究利用微擾法對速度及壓力進行雙重展開，求其流場型態及剪應力大小的公式，分析圓錐旋轉速度與變動頻率對流場型態與剪應力的影響。並比較轉動頻率對準靜態所估算的剪切力的影響，及雷諾數對平板上剪切力分佈的影響，以期能將結果應用於生物科技上。 Abstract A bioreactor can provide an environment for cultivating cells in vitro, so researchers have been using different bioreactors to observe the corresponding cellular responses to the mechanical stimulus. Among various kinds of bioreactors, cone-plate instrument has been used to provide the fluid shear stress from laminar to turbulent flow, which may simulate pulsatile shear stress encountered by the endothelial cells in the arterial circulation. Using the cone-plate instrument as the bioreactor, we analyze the stress field induced by periodically rotating the cone on the plate. The flow field is investigated by expanding the Navier-stokes and continuity equations with two nondimensional parameters, the Reynolds number (accounting significantly for the rotation speed) and the square of Womersley number (accounting significantly for the rotation frequency). We find the secondary flow and the shear stress on the plate are seriously influenced by the periodic motion of the cone. When the value of Womersley number increases, the quasi-steady solution of shear stress is no longer suitable.
