Flood Inundation Modelling for Mid‐Lower Brisbane Estuary

This study utilizes a two‐dimensional hydrodynamic model to calibrate and validate an inundation model for the Brisbane River estuary in Queensland, Australia. The bathymetry data used in the hydraulic model are derived from one arc second (1 s) shuttle radar topography mission digital elevation model, and the two‐dimensional hydraulic model is parameterized using the generated bathymetry with four open boundaries with water level observations and roughness coefficients. The calibration performance is evaluated by comparing the simulated results with the digitized records during the January 2013 flood event (a low magnitude event) at three gauging stations. The calibrated model is validated with water level data and available discharge data during the January 2011 flood (a large magnitude event) at four gauging stations located along the Brisbane River. Different performance indices are applied to demonstrate that the developed model performs well during calibration and validation. A sensitivity analysis is presented to assess the influence of riverbed elevation changes on the model because the main uncertainty of the model is the bathymetry data. The proposed model with the shuttle radar topography mission digital elevation model‐derived riverbed elevation for the Brisbane estuary is able to predict the flood inundation extent at an accuracy of 66.9% which is higher than or comparable with the accuracies of the existing studies. However, it is expected that the accuracy will increase if some improved bathymetry data become available in the future. Copyright © 2016 John Wiley & Sons, Ltd.     

A data porting tool for coupling models with different discretization needs

The presented work is part of a larger research program dealing with developing tools for coupling biogeochemical models in contaminated landscapes. The specific objective of this article is to provide researchers with a data porting tool to build hexagonal raster using information from a rectangular raster data (e.g. GIS format). This tool involves a computational algorithm and an open source software (written in C). The method of extending the reticulated functions defined on 2D networks is an essential key of this algorithm and can also be used for other purposes than data porting. The algorithm allows one to build the hexagonal raster with a cell size independent from the geometry of the rectangular raster. The extended function is a bi-cubic spline which can exactly reconstruct polynomials up to degree three in each variable. We validate the method by analyzing errors in some theoretical case studies followed by other studies with real terrain elevation data. We also introduce and briefly present an iterative water routing method and use it for validation on a case with concrete terrain data.     

一种新的InSAR基线估计方法

针对InSAR技术中基线估计误差对DEM精度的影响,从传统的基线估计方法入手,提出了一种新的估计基线参数的方法,并用仿真实验做了论证.结果表明,该方法比以往传统的方法得到的基线参数的精度更高,运算速度更快,应用范围更加广泛.     

基于EDEM的混凝土板桩静压贯入过程三维颗粒流数值模拟

针对混凝土板桩在干粗砂地基中的静压贯入问题,为了明确贯入过程中的挤土效应及贯入阻力的发展规律,利用离散元数值模拟软件EDEM(Engineering Discrete Element Method)对干粗砂中混凝土板桩静压贯入过程进行了三维数值模拟。为此,提出了适用于类似试验的参数标定方法,分析了贯入过程中颗粒的运动特征。针对板桩结构的特点,对长边和短边方向的挤土效应进行了对比,并以短边为例,分析了不同高度处的挤土效应。最后,根据颗粒与桩结构的接触力,提取了桩端阻力和桩侧摩阻力的值,分析了两者在贯入过程中的变化规律。结果显示:在贯入过程中,颗粒的运动呈现"涡流状",并随贯入过程演化;板桩沿短边方向的表面隆起量约为沿长边方向的隆起量的2倍;随着长宽比的增加,板桩结构在短边方向和长边方向的隆起值相应增加,且短边方向的隆起值与长边方向的隆起值的比值与相应板桩的长宽比近似相等;随着贯入的进行,桩侧摩阻力所占的比重逐渐增加,在完全贯入后,侧摩阻力值约占桩端阻力的1/25;不同长宽比的板桩结构,其桩端阻力和桩侧摩阻力的单位值近似相等,并与准二维计算结果相近。     

基于DEM的兰州市城关区黄河以北地区荒山造地方案研究

在平地少、山地多的兰州,开发荒山、利用荒山将是兰州市城市发展的一种新的战略选择,是突破发展瓶颈制约、拓展城市发展空间、缓解大气污染的有效途径.以城关区黄河以北地区为例,在2.5 m×2.5 m高分辨率DEM的基础上,通过修改原有地形使之满足一定的约束条件:①满足城市建设用地的坡度要求;②满足局部挖方和填方的平衡.并在此基础上,以GIS空间叠加分析的方式对开发荒山得到的平地进行城市建设用地适宜性评价,为荒山造地的具体实施提供切实可行的方案和依据.     

视点相关的真实感三维风景区模拟研究与实现*

提出采用八叉树组织真实山体数据,根据视点距离采用不同的细节层次LOD表示山体各部分,并结合视觉剪裁和帧间相关性进一步减少绘制的山体,达到加速三维地形的绘制和漫游的目的。使用混合纹理映射、阴影渲染技术,并加入山谷中的水面模拟,生成具有真实感的大规模三维风景场景。实验结果表明该方法有效地减少了算法复杂度,易实现碰撞检测,大大提高了绘制效率,在PC机上能实时地生成高分辨率、具有真实感的场景,完全满足VR交互要求。     

Study of filtered interphase heat transfer using highly resolved CFD–DEM simulations

Accurately predicting the complex inhomogeneous heat transfer behavior in gas–solid fluidized beds is of fundamental importance. In this work, we constitute an enhanced filtered interphase heat transfer coefficient (IHTC) closure by systematically filtering the dataset from highly resolved three-dimensional (3D) computational fluid dynamics–discrete element model simulations. Particularly, effects of several potential filtered variable markers on filtered IHTC predictions are examined by statistical analysis. We reveal the formulated filtered IHTC correction closure manifests a systematic dependence on filtered interphase temperature difference as an additional marker. The proposed closure shows good agreement with the filtered fine-grid simulation data in an a priori analysis. Moreover, the difference of filtered IHTC corrections deduced from 3D Euler–Euler and Euler–Lagrange simulations is quantified. Finally, the comparative analysis between our proposed filtered IHTC formulation and those in literature is implemented. This work holds a potential to facilitate the development of thermal gas–solid flow modeling.     

基于GIS的乌江流域新安江模型参数率定

为了使新安江模型的运用更能真实反映流域的基本特征及产汇流机理,利用地理信息系统空间分析的功能,由数字高程模型导出乌江武隆以上流域的流域排水网,并在此基础上提取汇流长度及坡度等地形特征值。在地理信息系统平台上,计算出流域下垫面的植被、土壤、地貌等特征值,并将其与流域模型参数建立相关关系。结果表明,各流域模拟的确定性系数及模拟精度均较高。因此,预报结果更加合理,理论依据也更加可靠。     

鄱阳湖湖区及五河七口DEM制作

阐述了在ArcGis平台上利用数字地形图生产鄱阳湖湖区及五河七口DEM制作的方法.