海底峡谷内浊流流动与沉积特征数值模拟研究

数值模拟已成为研究海底浊流的重要方式，开展海底浊流的流动与沉积特征的数值模拟，对深水沉积体系特征研究、海底工程设施稳定性评价以及深海油气勘探均具有重要意义。本文基于不可压缩流体Navier-Stokes方程与湍流k-ε模型构建了浊流数值计算模型，设定不同粒径、速度与悬浮颗粒物浓度等初始条件，模拟并分析了单粒径悬浮颗粒驱动的持续入流的海底浊流沿海底连续坡折带的流动过程及沉积特征。模拟结果显示，浊流在斜坡段处于加速状态，水平段流速骤减并逐渐沉积，且浊流在小坡度的加速不改变浊流的沉积趋势。浊流由于环境水体的夹带效应逐渐增厚，且浊流头部形态与流动特征与实测资料吻合良好。本文另对多频次持续入流浊流进行了模拟，并将模拟结果与实测地层沉积特征对比，结果显示，多频次持续入流的海底浊流在纵向上可能会形成多个不连续鲍玛层序的叠积。

Numerical simulation of turbidity current and sediment characteristics in submarine canyons

Numerical simulation has become an important way to research the turbidity current on the seabed. The numerical simulation of the current and sedimentary characteristics of the turbidity current on the seabed is significance to the deep water sedimentary system, the stability evaluation of seabed engineering and the deep-sea oil and gas resource exploration. A numerical model based on Navier-Stokes equation and the turbulence k-ε model for the simulation of turbidity current is applied to study the current and deposition of turbidity current with constant inflows into continuous slope breaks. Initial conditions such as different particle size, velocity and suspended particle volume fraction were set in the simulation. Simulated results show that the averaged velocity of the turbidity current accelerates at the slope, on the nearly horizontal bed, velocity drops obviously and gradually deposits at the horizontal bed. The acceleration of turbidity current at small slope does not affect the deposition trend. The thickness of the current gradually increases due to the environmental water entrainment, and the turbidity current head shape and flow characteristics are conformed favorably with the measured data. In addition, this paper also simulates the turbidity current of multi-frequency continuous inflow, and compares the simulation results with the measured sedimentary characteristics. The results show that the deposition of multi-frequency continuous inflow turbidity current may form the superposition of several discontinuous bauma sequences on the vertical strata.