In this study, we carried out a series of physical experiments using a submersed flume model to investigate how sand/clay content influences the depositional mechanism of submarine debris flows. A three-dimensional biphasic numerical model, with a Herschel-Bulkley rheology, was used to back-analyze the physical experiments. The calibrated numerical model was then used in a back-calculation to investigate the effects of viscosity on the deposition process. The results show that as submarine debris flows mix with water during the deposition process, shear stress at the slurry-water interface generates a vortex that leads to a swirl-wedge front head. High-viscosity slurry flows with a swirl-wedge front head travel at a higher aspect ratio and with a greater radius of rotation. Hydroplaning was observed when the front head was lifted by water during flow. The lifting height increased with flow depth fluctuation. Higher viscosity slurry was found to lift more rapidly due to its larger vortex and the decrease in density at the front head over time, both of which promote fluctuation. Although a high-density slurry has a greater lifting height, the ratio of lifting height to front head height is lower, indicating a smaller lifting force influence. Lower density flows have higher kinetic energy as the transfer of potential energy into kinetic energy is more efficient. Kinetic energy dissipation comprises three stages: (1) gravity-dominated coherent flow and hydroplaning lead to a rapid increase in kinetic energy; (2) sharp reduction in kinetic energy as slurry mixes with water, coherence and hydroplaning are reduced, and the influence of the shear stress increases; (3) slurry mixed very well with water, turbidity current dominates the kinetic energy dissipation. High-density slurry dissipates quicker in the last two stages. In stage 3, which dominates the temporal evolution of the debris flow, the Froude number is lower than 1, the flow thins and elongates, and the deposition process of submarine debris flows is dominated by gravity, and the difference of morphology of the different cases become clear.

中文翻译：

---

通过物理和数值模拟研究粘土/砂含量对海底泥石流沉积机制的影响

在这项研究中，我们使用沉水槽模型进行了一系列物理实验，以研究砂/粘土含量如何影响海底泥石流的沉积机制。具有 Herschel-Bulkley 流变学的三维双相数值模型用于对物理实验进行反向分析。然后将校准的数值模型用于反算以研究粘度对沉积过程的影响。结果表明，随着海底泥石流在沉积过程中与水混合，泥浆-水界面处的剪切应力会产生涡流，导致涡流楔形前端。具有涡流楔形前端的高粘度浆液以更高的纵横比和更大的旋转半径流动。当流动过程中前头被水抬起时，观察到打滑。提升高度随着流深波动而增加。发现较高粘度的浆液由于其更大的涡流和前端密度随时间的推移而上升更快，这两者都会促进波动。高密度浆体虽然提升高度较大，但提升高度与前头高度的比值较低，说明提升力影响较小。较低密度的流动具有较高的动能，因为势能转化为动能的效率更高。动能耗散包括三个阶段：（1）重力主导的相干流和滑水导致动能快速增加；(2)随着泥浆与水混合，动能急剧减少，减少了粘着性和滑水，且剪应力的影响增大；(3) 泥浆与水充分混合，浊流支配动能耗散。高密度浆料在最后两个阶段消散得更快。在主导泥石流时间演化的阶段3，弗劳德数小于1，流变细拉长，海底泥石流沉积过程以重力为主，不同情况下的形态差异变得清晰。