Collaborative Research: The effect of sand fraction and event evolution on fine-sediment transport and the depositional record in wave-supported mud flows

第 1 部分 通过波浪支撑重力流 (WSGC) 在大陆架上输送细小沉积物是沉积物从源头运至汇的关键组成部分，但人们对此仍知之甚少。该过程的当前模型侧重于淤泥和粘土大小颗粒的悬浮和运输。然而，最近的实验室实验表明，即使沉积层中的少量沙子也可能对输运层的动力学产生主导控制。拟议的工作将研究砂粒分数对 WSGC 沉积物输运的影响，特别是输运模式、下坡输运和沉积特征之间的转变。这些目标将通过一系列全面的实验室实验、3D 湍流解析数值模拟以及对 WSGC 活动大陆边缘现有现场数据的重新分析来实现。这项工作涉及广泛的领域，从流体力学和水资源工程到生物地球化学循环研究。外展活动包括通过在大学实验室进行的动手实验向 K-12 学生介绍沉积过程的相关性，并受邀到当地学校进行演讲。 本科生和研究生都将参与其中。除了期刊论文和会议演示之外，开源代码还将通过社区表面动力学建模系统 (CSDMS) 框架进行传播。 第 2 部分 通过波浪支撑重力流 (WSGC) 在大陆架上输送细粒沉积物是沉积物源沉的关键组成部分，但人们对此仍知之甚少。该过程的当前模型侧重于淤泥和粘土大小颗粒的悬浮和运输。然而，最近的实验室实验表明，即使沉积层中的少量沙子也可能对输运层的动力学产生主导控制。拟议的工作研究了 WSGC 中砂粒分数对沉积物输运的影响，特别是输运模式、下坡输运和沉积特征之间的转变。该项目围绕两个主要目标：1) 确定砂粒成分在控制 WSGC 内的动力学和输运以及与之相关的床层沉积物中的作用。 2) 评估事件演化（风暴的涨落）对重力流内沉积物和流动动力学的影响以及由此产生的沉积特征。这些问题将通过一系列全面的实验室实验、3D 湍流解析数值模拟以及对活动大陆边缘 WSGC 现有现场数据的重新分析来解决。这项工作涉及广泛的领域，从流体力学和水资源工程到生物地球化学循环研究。外展活动包括通过在大学实验室进行的动手实验向 K-12 学生介绍沉积过程的相关性，并受邀到当地学校进行演讲。 本科生和研究生都将参与其中。除了期刊论文和会议演示之外，开源代码还将通过社区表面动力学建模系统（CSDMS）框架进行传播。

Part 1Offshore delivery of fine sediment on the continental shelf via wave supported gravity currents (WSGC) is a key component of sediment transport fromsource to sink, yet it remains poorly understood. Current models of this process focus on suspension and transport of silt and clay sized particles. However, recent laboratory experiments show that even a small amount of sand in the sediment layer may exert a dominant control on the dynamics of the transport layer. The proposed effort will investigate the effect of sand fraction on sediment transport in WSGC, particularly, the transition between transport modes, the downslope transport and the depositional signatures. The objectives will be addressed using a comprehensive series of laboratory experiments, 3D turbulence-resolving numerical simulations, and re-analysis of existing field data from WSGC on active continental margins. The work is relevant to a broad range of fields, from fluid mechanics and water resource engineering, to studies of biogeochemical cycles. Outreach include introduction of the relevance of sedimentary processes to K-12 students with hand-on experiments in the university labs, and invited presentations to local schools. Undergraduate and graduate students will be involved. In addition to journal papers and conference presentations, open-source codes will be disseminated through Community Surface Dynamics Modeling System (CSDMS) framework.Part 2Offshore delivery of fine sediment on the continental shelf via wave supported gravity currents (WSGC) is a key component of sediment source to sink, yet it remains poorly understood. Current models of this process focus on suspension and transport of silt and clay sized particles. However, recent laboratory experiments show that even a small amount of sand in the sediment layer may exert a dominant control on the dynamics of the transport layer. The proposed effort investigates the effect of sand fraction on sediment transport in WSGC, particularly, the transition between transport modes, the downslope transport and the depositional signatures. The project is formed around two main objectives: 1) Determine the role of the sand fraction in controlling dynamics and transport within WSGC and the bed deposits associated with them. 2) Evaluate impacts of event evolution (surging and waning of a storm) on the sediment and flow dynamics within a gravity flow and the resulting depositional signatures These will be addressed using a comprehensive series of laboratory experiments, 3D turbulence-resolving numerical simulations, and re-analysis of existing field data from WSGC on active continental margins. The work is relevant to a broad range of fields, from fluid mechanics and water resource engineering, to studies of biogeochemical cycles. Outreach include introduction of the relevance of sedimentary processes to K-12 students with hand-on experiments in the university labs, and invited presentations to local schools. Undergraduate and graduate students will be involved. In addition to journal papers and conference presentations, open-source codes will be disseminated through Community Surface Dynamics Modeling System (CSDMS) framework.