Collaborative Research: Form, Spacing and Internal Structure of Eolian Ripples

尽管它们在今天的沙漠和沿海地区无处不在 尽管它们在地质记录中很重要， 为了理解现代运输过程， 对于风和大气之间复杂的相互作用， 沙负责形成风成涟漪，并为 伴生微地层学 我们建议研究这个最小的 通过模拟直接延伸的风成床型 之前的分析工作。 涟漪将从出生到 他们的成熟，有限的振幅状态，其中分散的 波浪之间的速度迫使波纹之间的相互作用， 导致平均波长的增长和衰减， 标准差随时间变化 多粒度系统将 在理解了单分散体系之后， 得到了 由此产生的微地层学将被跟踪，因为它 发展起来的 波纹将通过元胞自动化方法建模 已经被证明可以产生逼真的床型形状， 运动，物理上模拟实际中颗粒的运动， 涟漪 驱动涟漪动力学的跃移撞击事件 将通过模拟个别影响以及 与使用以下方法收集的跃移碰撞数据的比较： 高速摄影技术。 后一项工作正在 在阿伯丁大学由B.B.博士进行。威利茨， 我们有一个N.A.T.O.旅行合作补助金。 对涟漪场性质的附加约束， 它们在稳定状态下进化，将使用新的 在风洞中以及在 加州南部的沙丘。 方法和 建议的研究结果应该有一个有益的 对沉积物输运的一般影响，包括 水下系统

Despite their ubiquity in present-day deserts and coastal regions, and despite their importance in the geological record and for the understanding of modern transport processes, no general theory exists for the complex interactions of wind and sand responsible for the formation of eolian ripples, and for the associated micro-stratigraphy. We propose to study this smallest class of eolian bedforms through simulations that directly extend prior analytical work. Ripples will be followed from birth to their mature, finite amplitude state, where the dispersion of velocities among waves forces interactions between ripples that result in the growth of the mean wavelength and decay of its standard deviation through time. Multiple grainsize systems will be addressed after an understanding of the monodisperse system is obtained. The resulting micro-stratigraphy will be tracked as it develops. Ripples will be modeled by cellular automation methods that have been shown to produce realistic bedform shapes and motion, and that physically mimic the motion of grains in actual ripples. The saltation impact events that drive ripple dynamics will be studied by simulation of individual impacts as well as by comparison with data on saltation collisions collected using high-speed photographic techniques. This latter work is being carried out at the University of Aberdeen by Dr. B.B. Willetts, with whom we have a N.A.T.O. travel collaboration grant. Additional constraints on the nature of ripple fields, both as they evolve and at steady state, will be derived using newly developed photographic techniques both in the wind tunnel and in local dunefields in southern California. Both the methods and the results of the proposed research should have a salutary effect upon the general field of sediment transport, including subaqueous systems.