浑水异重流水量掺混系数的研究

Studies on water entrainment coefficient of turbid density currents

本文综合作者和前人的浑水异重流的掺混实验资料,得到在急流异重流时,其掺混系数同盐水异重流实验结果类似,当理查森数Ri在0.6-0.8时,可视为零掺混,而在接近缓流时,由于异重流挟运细粒泥沙,异重流在长距离运动中,有一部分分离出清水从下层进入上层,显示为负掺混。最后用经验公式表达异重流水流流速和交界面高程沿纵向的变化。

By analyzing the author＇s and other researchers＇ test data of turbid density currents,it was found that the entrainment coefficient of turbid currents was similar to that of saline current when the Froude number exceeded 1.Analyses showed that when Richardson Number Ri=0.6-0.8,there is no entrainment to occur.While for small slopes,due to turbidity current carrying fine sediment particles,a small part of water seeped from the lower layer into the upper layer,resulting in so called negative entrainment.An empirical relationship between water entrainment coefficient and Richardson Number for turbid density current is developed by using experimental data obtained in test flumes of steep and mild bottom slopes.This curve can be used for the calculation of density current velocity and interface elevation variation in longitudinal direction.