Sedimentation from forced wall jets versus free gravity flows: integrating tank experiments and field data into a physics-based depositional model

强制壁射流与自由重力流的沉积：将储罐实验和现场数据集成到基于物理的沉积模型中

• 批准号: 407609989
• 负责人: Dr. Jörg Lang
• 金额: --
• 依托单位: Abteilung 3 - Unterirdischer Speicher- und Wirtschaftsraum
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/407609989?language=en
• 关键词: Sedimentation; forced; wall; jets; versus

Recently, the impact of Froude supercritical density flows on deepwater clastic depositional systems has been increasingly recognized. These deposits are mainly preserved in the regions of expanding flows, where the aggradation is highest. Such regions of expanding flow can be modeled as supercritical jet flows. Submerged plane-wall jet flows, which emerge from an orifice into a standing water body and decelerate, can be considered as basic model for depositional processes related to expanding, point-sourced flows, like submarine fans and subaqueous ice-contact fans. The morphodynamics of expanding supercritical flows have a large impact on the dispersal of sediment and the resulting depositional architecture of subaqueous ice-contact fans, deposited by jet flows, and submarine fans, deposited by gravity flows, respectively. Jet flows and their deposits display a distinctive proximal to distal zonation. The densimetric Froude number exerts a primary control on the flow dynamics and the evolution from inertia-driven jets into density-driven gravity flows. The transition between plane-wall jets and gravity flows has a large impact on the deposition by expanding flows. The existing knowledge of jet flows and gravity flows, their hydrodynamic and morphodynamic evolution, and their deposits is insufficient to explain the characteristic bedform and facies successions. This project is designed to investigate these two flow types and develop recognition criteria for their deposits by integrating observations from tank experiments and field data. In the experimental part of the project, the morphodynamics of jet flows and gravity flows will be characterized in tank experiments, enabling the systematic variation of the controlling flow and sediment parameters. In the field part of the project, deposits related to zones of flow expansion from coarse-grained supercritical submarine fans will be studied. These field examples must enable a detailed characterization of the depositional architecture and facies successions and provide sufficient detail to invert for flow forcing. By the integration of the observations from the experiments and the outcrops a generic, physics-based model for deposition by expanding supercritical density flows will be developed.

近年来，弗劳德超临界密度流对深水碎屑沉积体系的影响日益得到认识。这些沉积物主要保存在流量扩大的地区，那里的加剧程度最高。这种膨胀流区域可以建模为超临界射流。浸没的平面壁射流从孔口进入静止水体并减速，可以被视为与膨胀的点源流（如海底扇和水下冰接触扇）相关的沉积过程的基本模型。膨胀超临界流的形态动力学对沉积物的扩散以及由此产生的水下冰接触扇（通过射流沉积）和海底扇（通过重力流沉积）的沉积结构有很大影响。急流及其沉积物表现出独特的近端到远端的分区。密度弗劳德数对流动动力学以及从惯性驱动射流到密度驱动重力流的演变发挥主要控制作用。平面壁射流和重力流之间的过渡对膨胀流的沉积有很大影响。现有的关于射流和重力流、它们的流体动力学和形态动力学演化以及它们的沉积物的知识不足以解释特征层状和相层序。该项目旨在研究这两种流动类型，并通过整合储罐实验和现场数据的观察结果来制定其沉积物的识别标准。在该项目的实验部分，将在水槽实验中表征射流和重力流的形态动力学，从而实现控制流量和沉积物参数的系统变化。在该项目的现场部分，将研究与粗粒超临界海底风扇流动扩展区域相关的沉积物。这些现场实例必须能够详细描述沉积结构和相层序，并提供足够的细节来反演流动强迫。通过整合实验和露头的观测结果，将开发出一种基于物理的通用模型，用于通过扩展超临界密度流进行沉积。