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| 1 | Well-balanced numerical modelling of non-uniform sediment transport in alluvial rivers显示文摘The last two decades have witnessed the development and application of well-balanced numerical models for shallow flows in natural rivers.However,until now there have been no such models for flows with non-uniform sediment transport.This paper presents a 1D well-balanced model to simulate flows and non-capacity transport of non-uniform sediment in alluvial rivers.The active layer formulation is adopted to resolve the change of bed sediment composition.In the framework of the finite volume Slope Llmiter Centred(SLIC) scheme,a surface gradient method is incorporated to attain well-balanced solutions to the governing equations.The proposed model is tested against typical cases with irregular topography,including the refilling of dredged trenches,aggradation due to sediment overloading and flood flow due to landslide dam failure.The agreement between the computed results and measured data is encouraging.Compared to a non-well-balanced model,the well-balanced model features improved performance in reproducing stage,velocity and bed deformation.It should find general applications for non-uniform sediment transport modelling in alluvial rivers,especially in mountain areas where the bed topography is mostly irregular. | Honglu Qian Zhixian Cao Gareth Pender Huaihan Liu Peng Hu | 2015 | International Journal of Sediment Research2015，30，2： | 4 |
| 2 | 基于局部分级时间步长方法的水沙耦合数学模拟显示文摘基于局部时间步长(LTS)技术(即在每个计算网格采用局部允许的最大时间步长),建立新的水沙数学模型,提高计算效率.用非结构三角形网格离散计算区域,采用充分反映水-沙-床相互作用的平面二维完整控制方程组,利用有限体积法求解控制方程,用HLLC近似黎曼算子估算界面数值通量.对动床溃坝算例的计算表明,当选取合适的局部时间步长级数时,计算效率明显提高(节省计算时间幅度达到68%),精度满足要求.长江中游太平口水道的工程应用表明,该模型能够在保证精度的前提下,节省高达92%的计算时间. | 胡鹏 韩健健 雷云龙 | 2019 | 浙江大学学报(工学版)2019，53，4： | 4 |
| 3 | 特征流量级对窜沟形成和发展影响的数值研究显示文摘分汊河道心滩常常出现窜沟,使滩体活动性变强,影响河势稳定。窜沟的形成与发展主要是对不断变化的径流流量的综合响应,为了探究窜沟对于不同流量级径流响应的敏感程度,基于平面二维水沙耦合数值模型,研究不同流量级条件下初始为完整高大心滩的冲淤过程,数值再现了窜沟的形成和发展。研究表明,窜沟的形成与发展和特征流量紧密相关:(1)流量较小、水流不能漫滩时,水流走心滩左右两汊的主槽,窜沟无法生成;(2)中等流量、水流能漫滩,但滩面水深较小时,左右两槽水流交换在低洼的滩面发生,冲刷生成窜沟;(3)在大流量下,心滩基本没于水下,左右两槽水流交换减弱,没有窜沟生成。研究结果还显示,在不同的特征流量下,窜沟发生的位置会有摆动,且窜沟生成和发育的特征流量的量级在一定程度上取决于滩体的平面形态。在分汊河道心滩滩体稳定性研究方面,方法及结论具有参考价值。 | 雷云龙 胡鹏 曹志先 刘怀汉 李薇 | 2019 | 水力发电学报2019，38，4： | 4 |
| 4 | 基于水沙床耦合的滩槽冲淤模拟与疏浚量计算显示文摘为了提高疏浚量的预报准确度,将平面二维水沙床耦合数值模型应用于长江下游东流水道的滩槽演变和疏浚量计算,成功复演了2010年大水作用下主要的滩槽冲淤特征,西港航槽内计算疏浚量与实测疏浚施工方量的误差较小.分析影响疏浚量计算不确定性的主要因素.结果表明,计算网格尺寸对计算疏浚量有较大的影响,当网格尺度约等于或小于实测地形数据间隔时,计算疏浚量较一致,否则网格给疏浚量计算带来较大的不确定性;进口泥沙体积分数对计算疏浚量的影响较大. | 胡鹏 邓芍怡 赵自雄 曹志先 刘怀汉 贺治国 | 2021 | 浙江大学学报(工学版)2021，55，4： | 2 |
| 5 | Enhanced bed load sediment transport by unsteady flows in a degrading channel显示文摘Laboratory flume experiments were done to investigate bed load sediment transport by both steady and unsteady flows in a degrading channel. The bed, respectively composed of uniform sand, uniform gravel,or sand-gravel mixtures, always undergoes bulk degradation. It is found that both uniform and nonuniform bed load transport is enhanced greatly by unsteady flows as compared to their volumeequivalent steady flows. This enhancement effect is evaluated by means of an enhancement factor, which is shown to be larger with a coarser bed and lower discharges. Also, the fractional transport rates of gravel and sand in non-uniform sand-gravel mixtures are compared with their uniform counterparts under both steady and unsteady flows. The sand is found to be able to greatly promote the transport of gravel, whilst the gravel considerably hinders the transport of sand. Particularly, the promoting and hindering impacts are more pronounced at lower discharges and tend to be weakened by flow unsteadiness. | Zhijing Li Honglu Qian Zhixian Cao Huaihan Liu Gareth Pender Penghui Hu | 2018 | International Journal of Sediment Research2018，33，3： | 1 |
| 6 | A new mixing equation for bed material composition in bed form dominant conditions显示文摘Vertical mixing beneath the bed surface and its effect on sediment composition has long been underestimated. This paper proposes a mixing equation to illustrate the temporal and spatial variations of bed material composition for bed form dominant rivers. A continuous mass conservation equation for elevation-specific nonuniform bed material composition is initially presented. A vertical mixing equation is finally derived as a diffusion-type partial differential equation with a source term characterized by a vertical diffusion coefficient and the geometric dimensions of bed forms. Coupled with boundary conditions, this equation is further developed in a vertical mixing model at the scale of bed forms, in which the variations of bed material composition are clearly illustrated. The equation accounts for vertical exchange fluxes driven by bed form migration and their effect on bed material composition, which helps elucidate the mixing mechanism. In application to riverbed degradation, the proposed equation is capable to describe armoring development in consideration of the interior mixing, which provides more satisfying predictions for bed surface materials. The new mixing equation helps gain insight into predicting the variations of bed material composition during morphological changes. | Baozhen Jia Deyu Zhong | 2022 | International Journal of Sediment Research2022，37，4： | 0 |
| 7 | 网格尺寸及初始扰动对辫状河流演变模拟的影响显示文摘辫状河流是以沙洲与汊道的交错分布为主要特征的河网系统。采用水沙与河床耦合动力学二维数值模型,模拟了以推移质输移为主的辫状河流演变过程,探讨了网格尺寸及初始河床扰动对辫状河流演变的影响。结果表明,数值模型能较好模拟辫状河流的多种形态与动力学特征。首先,泥沙淤积形成沙洲并呈鱼鳞状分布于整个河道;随后,沙洲通过自身增长、分裂,并相互合并而发育;最后,沙洲形态保持相对稳定。当网格尺度大于某临界尺度时,网格尺度影响辫状指数和沙洲高度,尺度越大,辫状指数和沙洲高度越小,但不影响面积、周长、长轴和短轴长等沙洲形态特征。扰动类型及其量级是引起流场不均匀性从而触发沙洲形成的重要因素,但不影响辫状河流及其沙洲的形态特征。 | 王长金 胡鹏 | 2022 | 泥沙研究2022，47，4： | 0 |
| 8 | Uniform and graded bed-load sediment transport in a degrading channel with non-equilibrium conditions显示文摘Bed-load transport plays a critical role in river morphological change and has an important impact on river ecology.Although there is good understanding of the role of the variation of river bed grain size on transport dynamics in equilibrium conditions,much less is understood for non-equilibrium conditions when the channel is either aggrading or degrading.In particular,the relative role of different grain sizes in the promotion and hindering of the transport of coarse and fine fractions in a degrading channel has yet to be investigated.The current study attempts to provide new understanding through a series of flume experiments done using uniform and graded sediment particles.The experiments revealed coarser grain-size fractions for a poorly-sorted sediment,relative to uniform-sized sediment,reduced the transport of finer grains and finer fractions enhanced the transport of coarse grains.This hinderingpromotion effect,caused by relative hiding and exposure of finer and coarse fractions,increased with bed slope and decreased with relative submergence.In particular,as relative submergence increased,the graded fractions tended towards behaving more like their uniform-sized counterparts.Also,the bed-load parameter of the graded fractions increased more with a rise in bed slope than observed for the uniformsized counterparts.These results revealed,for degrading channel conditions,such as downstream of a dam,bed-load equations developed for uniform bed sediment are inappropriate for use in natural river systems,particularly in mountain streams.Furthermore,changes in river bed composition due to activities that enhance the input of hill-slope sediment,such as fire,logging,and agricultural development,are likely to cause significant changes in river morphology. | Khabat Khosravi Amir HNChegini James RCooper Prasad Daggupati Andrew Binns Luca Mao | 2020 | International Journal of Sediment Research2020，35，2： | 0 |
| 9 | 航道工程作用下福姜沙水道滩槽演变特性及对水沙过程响应的数值研究显示文摘福姜沙水道是长江南京以下12.5 m深水航道重点治理河段。航道工程实施后,仍需进行疏浚维护保障航道畅通。为了探究航道工程作用下福姜沙水道的滩槽演变特征,并进一步研究其对水沙过程的响应关系,采用基于Hybrid LTS/GMaTS方法的平面二维水—沙—床耦合数学模型进行了数值模拟研究。Hybrid LTS/GMaTS方法在不损失模型计算精度的前提下大幅度提高了计算效率。研究结果表明:1)水动力作用是洲滩变形的主要动力,体现在洲滩整体冲淤和局部形态改变两方面;2)航道工程作用下,福中水道入口处水动力条件明显改善,各特征流量级下均呈现刷深趋势,航道中段呈现“洪冲枯淤”的冲淤特征,主流被归顺在深槽内,且随着流量增长深槽向南摆动;3)边心滩演变和水动力作用共同影响福北水道航道冲淤变化,航道工程作用下靖江边滩、双涧沙沙舌、福北水道的滩槽演变关系和对径流特征响应过程发生根本性变化。对水道整体而言,航槽回淤现象得到显著改善,然而受到洲滩演变和局部水动力减弱的不利影响,福北水道入口处航道条件发生恶化。 | 孙孟喆 胡鹏 李有为 刘奇峰 曹志先 | 2022 | 海洋工程2022，40，6： | 0 |
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