In the tree crown, the basal area growth of trunk sapwood is approximately equivalent to that of the upper branch sapwood. 在树冠内，树干边材断面积生长量与其上部的枝条边材断面积生长量大致相等。
Time dependent calculation for a suddenly imposed pressure gradient has shown that variation of the cross sectional area reduces inertial effect in the contraction flow region. 压力差为阶跃变化的情况下数值计算结果说明了收缩部的断面积的时间变化减少了收缩部的惯性效果。
