长江口平面二维非均匀全沙数学模型

【作者】 曹振轶；

【导师】 丁平兴； 贺松林；

【作者基本信息】 华东师范大学 ， 自然地理学， 2002， 博士

【摘要】 河口海岸的泥沙问题涉及到人类开发河口海岸自然资源的活动，并且是陆海相互作用研究的重要组成内容之一，对它的研究具有重要的科学意义和应用价值。本文以长江口为例在前人工作的基础上，通过分析长江口水流、泥沙运动特性的基础上，建立平面二维的非均匀泥沙数学模型，并对长江口的泥沙输运过程和输运机理进行了研究。 长江口海域开阔，浅滩宽浅，风浪的作用显著，在水动力模型和全沙数学模型中考虑了波浪的作用。鉴于长江口悬沙和底沙组成与分布的不均一性，为了较好地反映悬沙与底沙的物质交换，本文提出了平面二维非均匀泥沙数学模型，保证以不同组份泥沙在长江口广阔区域内输运的物质守恒性。在泥沙数学模型中较为合理的考虑了不同粒径组泥沙的输运、沉降、再悬浮和细颗粒泥沙的絮凝问题。在确定悬沙絮凝沉速时综合考虑了泥沙粒径、盐度、含沙量及水流紊动的影响。针对长江口复杂的岸线，将水动力学方程和全沙数学模型转化为适应复杂边界的自适应网格下模型。悬沙输运方程采用破开算子的方法求解，平流项采用Ultimate Quickest格式求解，即保证了数值格式的守恒性，又消除了数值耗散。以上措施提高了计算的精度。通过实测资料对数学模型计算的结果的检验，表明该模型能反应长江口复杂自然条件的泥沙运动规律。借助通量分解和数学模型的方法分析了感潮河段含沙量变化规律。更多还原

【Abstract】 Sediment transport in estuarine and coastal is not only one of import problems when the human explore the natural, but also the one of major contents of Land and Sea Interactions in the Coastal Zone. So sediment research is interested for scientist and engineer. Based on the reviews of current research, an 2-D horizontal non-uniform sediment numerical model is established according to the character of hydrodynamic and sediment transport in Yangtze estuary.. The sediment transport process and mechanism is discussed.The Yangtze estuary is so wild, the mouth bars are long, the slope is gentle, so the wave action is importance. The wave effect is considered in hydrodynamic model and sediment model. A 2-D horizontal non-uniform sediment transport is established according to the different grain size in suspended sediment and bed load in Yangtze estuary, which could reflect the conservation during different sediment grain transport and exchange between suspended sediment and bed load. The fine sediment setting velocity due to flocculation is determined by sediment grain, salt, sediment concentration and flow turbulence. A boundary-fitted curvilinear coordinate system has been deployed to obtain a more accurate solution of SSC. The operator-splitting algorithm and the Ultimate Quickest scheme have been used to solve the sediment transport equation. The results calculated are in close agreement with field observation , which shows this model can predict sediment transport in Yangtze estuary. The reason induced SSC variety in tidal channel is discussed through the flux analysis and sediment model.更多还原