平行平板流动腔的数值优化设计

平行平板流动腔系统是研究切应力对细胞影响的体外实验装置之一。前期研究发现,流动腔的高度存在一个最佳高度,使用这个高度可以有效地减小或避免由于装配所引起的高度误差对切应力的影响。为了获得这一最佳高度,本文使用数值方法研究了平行平板流动腔的几何尺寸、流体粘度与集中液阻之间的关系,并拟合得到了集中液阻的函数关系式。利用液阻关系式和切应力计算公式,求得了对底部切应力影响最小的最佳高度的表达式。同时,研究还发现,对于相同的底部切应力,当高度取最佳高度时,所需的入(出)口压差最小。这样在流动腔底部沿轴向的压力梯度也就越小,沿轴向不同位置之间的压力差别也越小,这将有利于细胞力学实验结果之间的比较。

Numerical optimum design for parallel plate flow chamber

Parallel plate flow chamber,which usually has a very small chamber height for causing a uniform distribution of wall shear stress on the lower plate,is a kind of experimental apqaratus frequently used to examine the response of biological cells in vitro to a constant shear stress.Previous studies have revealed that the chamber height exist an optimum value to reduce efficaciously the effect of height assembling error on the wall shear stress on the lower plate.In this paper,the influence of fluid viscosity and the geometric sizes on the lumped resistance to flow in a type of common used parallel plate flow chamber is numerically studied,and an expression for lumped resistance is fitted.An optimum height of parallel plate flow chamber is derived from the lumped resistance expression and the wall shear stress expression.If the geometric sizes of parallel plate flow chamber are designed according to the optimum height,not only the effect of height assembling error on the wall shear stress on the lower plate can be reduced efficaciously,but also the differential pressure across the inlet and the outlet is minimum.It is advantageous to increase the comparability of experimental results in the cellular mechanics,because the minimum differential pressure means the minimum pressure gradient and the minimum pressure difference between two different points on the lower plate along the flow direction.