Jets that expand from an orifice into an ambient water body represent a basic flow model for depositional environments related to expanding flows. Momentum-dominated jets evolve into gravity-dominated density flows. To understand this transition and its sedimentological relevance, three-dimensional tank experiments with submerged wall jets were conducted, systematically varying parameters such as the initial density difference, bed slope, grain size and sediment supply. Bedform successions could be subdivided into those related to the jet and those related to the density flow. Jet deposits included early-stage bedforms, scours and mouth bars. Early-stage bedforms are asymmetrical dunes that spread concentrically from the orifice. Sediment entrainment by eddies from the expanding jets led to the formation of scours and mouth bars. Flows with lesser initial density difference produced more elongate scours. Conversely, scours became deeper for denser incoming flows. Coarser-grained sediment caused the formation of higher and steeper mouth bars and vice versa. The transition from momentum-dominated jets to gravity-dominated density flows occurred approximately at the mouth-bar crest. Hydraulic jumps were absent in the expanding jet regions and at the transitions to density flows. Instead, complex flow patterns and circulations were inferred from the velocity measurements within the scour and at the mouth-bar crests. Bedform trains related to the density flow were controlled by the grain size and sediment supply. Coarse-grained sediment and high supply rates caused strong mouth-bar aggradation and flow splitting, leading to the formation of bedform trains laterally adjacent to the mouth bar. Fine-grained sediment and low supply rates caused the formation of bedform trains downflow of the mouth bar. The symmetrical bedforms deposited by the density flows always displayed an in-phase relationship with the flow, indicating that they were antidunes. The experimental jet deposits resemble successions known from subaqueous ice-contact fans and deep water channel-lobe transition zones.

中文翻译：

---

三维浸没壁射流及其向密度流的过渡：形态动力学及其对沉积记录的影响

从孔口膨胀到周围水体的射流代表了与膨胀流有关的沉积环境的基本流动模型。动量支配的射流演变成重力支配的密度流。为了了解这种转变及其沉积学意义，我们进行了浸没式壁流的三维水箱实验，系统地改变了参数，例如初始密度差，河床坡度，粒度和沉积物供应。床形演替可以细分为与射流有关的和与密度流有关的。喷射沉积物包括早期床形，冲刷物和口条。早期床形是不对称的沙丘，从孔口同心地散开。不断膨胀的射流产生的涡流夹带了泥沙，形成了冲刷和口状条状物。初始密度差较小的流动产生更多的拉长冲刷。相反，对于更密集的流入，冲刷变得更深。粗粒状沉积物导致形成更高和更陡的河口条，反之亦然。从动量为主的射流到重力为主的密度流的转变大约发生在口杆波峰处。在扩展的射流区域和向密度流的过渡处没有水力跃迁。取而代之的是，从冲刷内和口岸波峰处的速度测量结果可以推断出复杂的流动模式和环流。与密度流有关的床形列车受晶粒度和沉积物供应的控制。粗大的沉积物和高的补给率​​导致强烈的口杆凝结和水流分裂，导致床形列车在侧向靠近口杆的位置形成。细颗粒的沉积物和较低的补给率导致了床形列车下降，形成了口杆下降。由密度流沉积的对称床形始终与流显示同相关系，表明它们是反沙丘。实验性射流沉积物类似于从水下冰接触风扇和深水通道裂片过渡区已知的演替过程。