MIKE泥沙模拟教程2

1、Theoretical Background理论背景MIKE 21/3 FM Mud Transport Module MIKE 21/3 FM泥模块MIKE 21/3 MT FM: Theoretical Background理论背景Introduction介绍Cohesive and non-cohesive sediment has different properties;粘性泥沙和非粘性泥沙的性质是截然不同的Question问题: What do we class as mud?什么是泥？Answer答案:Particle Sizes include: Silt: 2-63m. Cl

2、ay: less than 2m; 泥的颗粒粒径:粉沙: 2-63m.粘土 : 小于2m; At this scale ionic charges interact electrostatically and affect the properties of sediment-fluid interaction (flocculation, turbulence damping etc.); 在这个尺度上，颗粒所带的离子电荷作用，影响到了泥沙-水流的属性（絮凝，紊动阻力等）;Also, sediment properties are affected by organic material c

3、ontent; 泥沙的属性同时也受到有机物质的影响;Sand with a content of 10-20 per cent fine sediments treated as cohesive sediment. 沙中有10-20%的细颗粒可以当作是粘性泥沙。Mud泥Sand沙MIKE 21/3 MT FM: Theoretical Background理论背景MIKE 21/3 FM MT:Solves the 3-D AD equation with diffusion coefficients that are dependant on fluid as well as mud pr

4、operties; 求解三维的对流扩散方程，其中扩散系数考虑了流体和泥沙的属性ws = fall velocityws = 泥沙沉速T = turbulent Schmidt no.T= 湍流 Schmidt 数T= anisotropic eddy viscosityT= 各向异性涡粘系数S i = source or sink termfor erosion or depositionSi =冲刷和淤积作为源和汇MIKE 21/3 MT FM: Theoretical Background 理论背景Source and sink terms:源、汇项：Deposition: for b c

5、e(soft bed)(Parchure & Mehta, 1985) 再悬浮（软底床） Erosion: for b ce(hard bed) (Partheniades, 1963) 侵蚀（硬底床）Instantaneous bed shear stress(combined waves & currents)瞬时底床切应力(波流耦合)Critical shear stress for deposition临界淤积切应力Critical shear stress for erosion临界侵蚀切应力MIKE 21/3 MT FM: Theoretical Background理论背景Pro

6、cesses that are described in MT: MT中描述的物理过程:Deposition and erosion rates are based on the critical bed shear stress concept (R.B. Krone 1962, Parchure and Mehta 1985, Partheniades, 1963); 沉积率和侵蚀率基于底床临界剪切应力的概念 (R.B. Krone 1962, Parchure and Mehta 1985, Partheniades, 1963);Flocculation and hindered se

7、ttling included; 包括絮凝和受阻沉降;Density driven mud flow at high sediment concentrations; 高含沙量下的密度驱动浮泥流（异重流）；Damping of turbulence over the lutocline at high sediment concentrations; 高含沙量下紊动效应的衰减;Bed sediment variation in depth by a n layer bed description (n is typically 3, weak fluid mud, fluid mud and

8、consolidated bed); 底床泥沙分为n层描述（n一般为3，弱浮泥层，浮泥层和固结层）Consolidation in bed; 底床的固结；Enhancement of bottom shear stress from short periodic surface waves; 短周期波作用下底床剪切应力的增强；Other features of the MT model: MT模型的其他特点:3D description based on the MIKE 3 FM Advection-Dispersion with inclusion of erosion-depositio

9、n terms; 三维的MT模型基于MIKE-3 FM传输扩散模块，包含了侵蚀-沉积项；Applies the same mesh as MIKE 3 HD FM; 使用和MIKE-3 FM水动力相同的网格地形Is solved simultaneously with MIKE 3 HD FM; 和MIKE-3 FM水动力同时耦合计算；Spatially varying parameter settings allowing for effect of vegetation, biology and sediment inhomogenity; 参数设置可以随空间变化，可以反映植被，生物和泥沙

10、的不均一性。Can use boundary data from MIKE 21 FM; 可以使用MIKE 21-FM的边界数据；Multiple fractions and layers can be simulated. 可以模拟多组分，多层底床。MIKE 21/3 MT FM: Theoretical Background理论背景Input parameters: 输入参数：Settling velocity (measurable) 沉降速度 (实测)Flocculation (measurable)絮凝 (实测)Dry density of bed layers (measurabl

11、e)底床干密度 (实测)Critical shear stress for erosion (experience/measurements)临界侵蚀剪切应力 (经验/实测)Thickness of bed layers or estimate of total amount of sediment in the system (measurements) 底床厚度或模型中总的泥沙量 (实测)Concentration at open boundaries (measured or modelled) 边界处含沙量 (实测或从大模型提取)MIKE 21/3 MT FM: Theoretical

12、 Background理论背景Calibration parameters: 率定参数：Dispersion coefficients 扩散系数Critical shear stresses, for each layer 每个床层的临界剪切应力Erosion coefficients, for each layer 每个床层的侵蚀系数Power of erosion, for each layer 每个床层的侵蚀指数Transition coefficients between bed layers (consolidation) 底床各层之间的转换系数(固结)MIKE 21/3 MT FM

13、: Theoretical Background理论背景Output Parameters 输出结果:Suspended sediment concentrations in time series of 3D matrixes or 2D sections (horizontally or vertically) 三维矩阵或两维断面的悬浮含沙量浓度时间序列（水平或垂直）Height or density of bed layers底床高度或密度Net sedimentation rates 净淤积率MIKE 21/3 MT FM: Theoretical Background理论背景Disc

14、ussion and key points讨论与要点:Mud behaviour is extremely difficult to predict, and is subject to intense research activity. The models that exist today are continuously being improved. 对于泥沙运动规律的研究还远远不够，所以泥沙的运动很难预测。现在的泥沙模型处于不断改进中；It is important to define time scales of problem and modelled and choose a

15、n approach accordingly. 定义问题的时间尺度并且选择相应的解决办法，这一点是很重要的；Sediment behaviour is dependant on the hydrodynamical conditions. If these are modelled correctly the trends and overall behaviour can be assessed adequately. 泥沙的运动很大程度上取决于水动力条件。如果水动力模拟得足够准确，泥沙的运动趋势可以大体把握。Evaluation of relevant time scales for st

16、udy is vital. i.e. for long term simulations (months), giving seasonal variations and trends is more important than detailed process studies. 评估相应的时间尺度极为重要，例如，对于长期模拟（几个月） ，给出季度变化和趋势，比研究详细的过程更重要。Biggest problem is the lack of reliable measurements with which to calibrate the models. Ideally we require: time series of SPM, in-situ measurements of fall velocities, detailed sediment maps. 泥沙模拟最大的问题在于缺少可靠的实测资料来率定模型。理想情况下，泥沙模型需要：SPM时间序列，实测沉降速度，详细的底床泥沙分布图。3D mode