【作者】 朱曦； 曾玉红； 槐文信；

【Author】 ZHU Xi;ZENGYu-hong;HUAI Wen-xing;State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University;

【机构】 武汉大学水资源与水电工程科学国家重点实验室；

【摘要】 水媒植物种子作为河流中的有机沉积物,其沉降和输移特性与泥沙类似,取决于颗粒属性和周围流体特性。沉降速度和阻力系数对于种子在水体中的运动有着重要的影响。本研究基于各类无机沉积物的实验数据,采用非量纲直径和速度,依据球形颗粒阻力系数经验公式,考虑形状的不规则性,对汇总的非球形颗粒数据进行回归分析,得到了统一的阻力系数经验公式。以颗粒雷诺数100为分界的分段函数可以进一步提高公式的预测精度。相比于其他公式,本公式适用范围广,预测精度高。同时,实验测定了鄱阳湖区荷花,睡莲和菖蒲沉降速度和阻力系数,结合其他水生植物种子实验数据,结果表明本研究公式可用于模拟和预测非球形水媒植物种子沉降速度,进而丰富水媒传布动力研究,为湖库区生态系统恢复提供依据和指导。更多还原

【Abstract】 The settling velocity of irregular particles is affected by both particle properties(density,size,and shape) and fluid properties(density and viscosity) and is therefore a function of particle Reynolds number and particle shape.Experimental data from the literature have been collected on a wide range of particle Reynolds numbers(0.03-10000) to develop empirical formulae for drag coefficients and settling velocities of non-spherical particles.For coarse particles with large dimensionless diameter,the effect of shape on settling velocity is more significant,and thus piecewise formulae were derived to further improve prediction accuracy.Compared with other models,the newly presented formulae predict more accurately the settling velocity of irregular particles.Moreover,settling velocities of three types of hydrochorous seeds collected from Poyang Lake were measured in the laboratory and the comparison between the measured and predicted settling velocity shows that the empirical formulae can be applied to non-spherical granular hydrochorous seeds and can enrich the study on the dynamic pattern of hydrochory.更多还原