风沙与水沙运动多重时间尺度与深度积分模式

MULTIPLE TIME SCALES OF AEOLIAN AND FLUVIAL PROCESSES AND DEPTH-AVERAGED INTEGRAL MODELLING

针对风沙与水沙动力学研究的共性,提出风沙与水沙运动统一深度积分模式;在此基础上,将水沙运动过程多重时间尺度理论扩展至风沙运动,比较研究风沙与水沙运动向平衡状态调整的时间尺度特征.数值算例与风洞实验结果对比表明,积分平均模型能够基本准确地捕捉风沙运动的输沙率变化等基本特征;风沙与水沙运动的积分时间尺度比较分析表明,风沙运动与水沙运动类似,推移质运动能够很快地调整到平衡状态,而悬移质运动调整到平衡状态则需要相对较长的过程,在湍流悬移质实验和数值模拟研究中应考虑恢复平衡过程的影响.

A depth-averaged numerical model is introduced for aeolian sediment transport modeling. Model validity has been assessed using experimental data, and the results show that the major features of aeolian sediment transport can he well captured by the proposed model. Furthermore, based on the integral model, the recent theoretical work on the multiple time scales of fluvial processes is extended to aeolian processes, the corresponding time scales concerning the adaptation of sediment transport to equilibrium state are purposely defined and quantitatively analyzed. The results provide a theoretical justification for aeolian saltation that it can be adapted to equilibrium state very rapidly, while it is found that a much longer time and space is needed for aeolian suspension to adapt to equilibrium.