弯曲海底峡谷中浊流的三维流动及沉积的初步研究

海底浊流的运动及其沉积，是目前浊流研究的热点之一。根据经过验证的基于雷诺平均纳维尔-斯托克斯方程及浮力项修正 k-ε 湍流模型的三维数值计算模型模拟了海底弯曲圆弧形峡谷内的浊流的流动和沉积，结果表明:（1）浊流在运动过程中由于对环境水体的夹带厚度不断增加，浊流厚度一般会超过峡谷深度，溢出峡谷，使浊流产生密度和动量损失；（2）浊流到达弯道部分后，由于离心力的作用会产生剥离，溢出更多的浊流至漫滩区域。浊流剥离的最大处为弯道顶点外岸下游处，其过量密度可达入流的37.5%；（3）对于模拟的横剖面为圆弧型的峡谷内的浊流来说，弯道顶点处的二次流在底部形成一个顺时针的循环圈，靠近峡谷底部从外岸指向内岸；（4）在峡谷中间及弯道顶点内岸下游处形成沉积，在弯道顶点外岸下游处形成侵蚀。这些特征对根据浊流的沉积观察推测其形成环境及油气储层的调查等方面有一定的参考意义。

Preliminary Study of Three dimensional Flow and Deposition of Turbidity Currents in Sinuous Submarine Canyons

The characteristics of the flow and deposition of turbidity currents in deep-sea is a focus of present research. A three-dimensional computational model based on Reynolds-averaged Navier-Stokes equation and buoyancy modified turbulence k-ε model is used to study the flow and deposition of turbidity currents in a sinuous submarine canyon with arc cross-section. The findings are: (1) subaqueous turbidity current generally increases its thickness on its way downstream due to the entrainment of environmental fluid and spills over the bank as soon as its thickness exceeds the height of the canyon, resulting in mass and momentum losses; (2) at channel bend apex, much current strips out due to centrifugal force; the largest local stripping occurs just downstream the outer bank of the bend apex, excess density of the stripped current reaches as much as 37.5% that of inflow; (3) the secondary flow at canyon bend apex is river-like, i.e. directed from outer bank to the inner bank near the bed for the arc-shaped channel simulated; (4) in the canyon simulated, deposition occurs around canyon center and downstream the inner bank of bend apex, while erosion occurs downstream the outer bank of bend apex. Those features may assist us in reconstructing the ancient environments in exploring the submarine hydrocarbon reservoirs by observing the turbidites.