Collaborative Research: Micromechanics of Eolian Sand Dune Development: Computer Simulations and Field Experiments

Kocurek 9526708非线性动力学的新模型和计算技术以及改进的野外研究仪器促使人们重新审视风沙形成的问题。拟议调查的目标是为风沙和沙丘场的起源和演化提供先进的模型，计算出这些模型的预测结果，并对它们进行严格的现场测试。这项研究将采用综合方法，将计算机模拟、现场观察和实验以及分析模型结合在一起。这项研究的工作计划从考虑沙地(初始沙丘)成核开始，继续调查孤立的河床，逐步发展到处理河床之间的相互作用，最后研究沙丘场的整体动力学。在沙地的层面上，计算机模拟沙地上的跃迁加上现场实验的目的是为了了解为什么以及如何首先发生成核，然后是生长。在河床层面，将使用计算机模拟正在形成的河床上的气流和跃变，并通过详细的现场测量进行测试和约束，以探索演变为具有滑面的沙丘形态的条件。在床面-床面相互作用层面，将对沙丘的侧向和下风向气流进行广泛的现场测量，以探讨沙丘对邻近沙丘的调节作用。在各种条件下，各种建造的沙丘之间的相互作用将被记录下来，以产生描述沙丘-沙丘相互作用结果的功能图。这些结果将与床面力学的简化计算机模拟进行比较。预计将根据模拟和实地工作中出现的简化假设，得出沙丘地区发展的分析模型。在整个研究过程中，将探索在任何发展和相互作用水平上可能影响床型的因素，如风速和可变性以及沙子供应。对结果模型的预测将与自然沙丘区域的形态进行比较。

Kocurek 9526708 New models and computational techniques in nonlinear dynamics and improved instrumentation for field studies motivate a re-examination of the problem of eolian dune formation. The goals of the proposed investigation are to be advance models for the origin and evolution of eolian dunes and dune fields, to work out the predicted consequences of these models, and to subject them to rigorous field testing. The study will follow an integrated approach, bringing together computer simulation, field observation and experimentation, and analytical models. The work plan for the study proceeds in step-wise fashion from consideration of sand patch (incipient dune) nucleation, continuing with investigation of isolated bedforms, graduating to treatment of interactions between bedforms, and ending with study of the overall dynamics of dune fields. At the sand-patch level, computer simulations of saltation over sand patches plus field experimentation are aimed at understanding why and how nucleation first occurs and growth follows. At the bedform level, computer simulation of airflow and saltation over developing bedforms, tested and constrained by detailed field measurements, will be used to explore the conditions under which evolution to dune forms with slipfaces occurs. At the bedform-bedform interaction level, extensive field measurements of airflow lateral and downwind from dunes will be performed to probe the regulating effects of dunes on their neighbors. The interactions between a variety of constructed dunes under a range of conditions will be documented to produce a functional map describing the results of dune-dune interactions. These results will be compared to simplified computer simulations of bedform mechanics. It is expected that an analytical model of dune field development, based on simplifying assumptions emerging from the simulation nd field efforts, will result. Throughout the entire study, factors that may affect bedforms at any of the levels of development an d interaction, such as wind velocity and variability and sand supply, will be explored. Predictions of the resulting model will be compared with the morphology of natural dune fields.