MIKE泥沙模拟教程2.pptx

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,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:2-63,m.Clay:less than 2,m;,泥的颗粒粒径,:,粉沙,:2-63,m.,粘土,:,小于,2,m;,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 content;,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 properties;,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,w,s,=fall velocity,w,s,=,泥沙沉速,T,=turbulent Schmidt no.,T,=,湍流,Schmidt,数,T,=anisotropic eddy viscosity,T,=,各向异性涡粘系数,S,i,=source or sink termfor erosion or deposition,S,i,=,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,ce,(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¤ts),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,Processes 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(RB.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 settling 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 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-deposition 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(measurable),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 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: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,Discussion 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 an 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 study 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 models can realistically only simulate shorter events.These events must be carefully selected such that the all important flow and sediment conditions are covered.,由于计算耗时的限制，三维模型只能模拟较短的时段。这些时段应该经过精心挑选，能够包含所有重要的水动力条件和泥沙,条,件。,MIKE 21/3 MT FM:Theoretical Background,理论背景,