Axial flow through gaps between aligned straight yarns with realistic cross-sectional shapes, described by power-ellipses, was analysed numerically. At a given fibre volume fraction, equivalent gap permeabilities have a maximum at minimum size of elongated tapering parts of the gap cross-section and a ratio of gap width to height near 1. When the yarn spacing is given in addition to the fibre volume fraction, calculated maximum and minimum values for the equivalent permeability of inter-yarn gaps, which occur at near-rectangular and lenticular cross-sections, differ by factors of up to 3.3. Novel approximations for the shape factor and the hydraulic diameter in Poiseuille flow were derived as a function of the fibre volume fraction, the yarn cross-sectional aspect ratio and the geometrical parameter describing the shape of the power-elliptical yarn cross-section. This allows the equivalent gap permeability to be predicted with good accuracy for any fibre volume fraction and yarn cross-section.

数值分析了通过力椭圆描述的，具有逼真的横截面形状的对齐直线纱线之间的缝隙的轴向流动。在给定的纤维体积分数下，等效的缝隙渗透率在缝隙横截面的细长锥形部分的最小尺寸处最大，并且缝隙宽度与高度的比率接近1。 ，在近似矩形和双凸透镜横截面处发生的纱间间隙等效磁导率的计算最大值和最小值相差最大3.3倍。推导了Poiseuille流中形状因子和水力直径的新颖近似值，它是纤维体积分数的函数，纱线横截面纵横比和描述强力椭圆形纱线横截面形状的几何参数。这样就可以对任何纤维体积分数和纱线横截面，以良好的精度预测等效的间隙渗透率。