Application of nonlinear dynamics to hydro-geomorphology

非线性动力学在水文地貌学中的应用

• 批准号: 16360242
• 负责人: SHIMIZU Yasuyuki
• 金额: $ 9.41万
• 依托单位: HOKKAIDO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16360242/
• 关键词: weakly nonlinear stability analysis; stream; double-row bar; dune; non-uniform sediment bed; 網状化; 画像計測; 数値計算モデル; 谷低平地; 中規河床波; 弱非線形解析; デューン; 復列砂州; 乱流; 浮遊砂; 平衡状態砂洲波高; 植生; 小規模河床波; 非線形解析; 圧力勾配; リップル; 乱流モデル

A weakly nonlinear analysis considering the interference between alternate bar and double-row bar has been developed. Findings show that when the two modes are on the same order, the mode cross interference controls development process of each wave and they cannot grow simultaneously. The development process of bars is strongly influenced of the mode cross interference. Hydraulic experiments and the weakly nonlinear analysis, by setting several hydraulic conditions under which either alternate bars or double-row bars formed, have been conducted to clarify a changing process of bar shape formed during flood at usual time. It is found that the channel shape at usual time is strongly affected by the bar shape during flood.Effect of unsteady characteristics of flow and vegetation growth on number of braided streams and temporal stability of streams has been studied. The results show that the number of streams decreases and temporal change of streams is suppressed with vegetation under unsteady flow conditions. Furthermore, dynamic characteristics of bars on bed with non-uniform sediment have been studied. The results show that bar geometry on bed with non-uniform sediment has been changed with time and does not approach equilibrium state.A new model was proposed taking proper account of the functional relation between the Froude number and the Shields number by revisiting the existing weakly nonlinear stability analysis of the transition of dune and flat bed regimes. It is found that, from the analysis, the dune-flat bed transition is characterized by subcritical bifurcation in the range of relatively small average bed slopes, and large velocity coefficient. In addition, Izumi extended the existing model of the inception of channels to the more general cases in which the base state slope profile is arbitrary given. The analysis shows that the spacing of channels is approximately one thousand times the depth of surface flow on slopes.

建立了考虑交错杆与双排杆干涉的弱非线性分析方法。结果表明，当两个波模处于同一阶时，模交叉干涉控制着两个波的发展过程，两个波不能同时增长。模式交叉干涉对杆件的发展过程有很大的影响。通过设置不同的水力条件，进行了隔排沙和双排沙的水力学试验和弱非线性分析，阐明了在平时洪水作用下沙的形态变化过程。研究发现，洪水期河道形态对平时河道形态有很大影响，水流非恒定特性和植被生长对分汊河道数量和分汊河道时间稳定性的影响。结果表明，在非恒定流条件下，植被减少了河流的数量，抑制了河流的时间变化。此外，还研究了非均匀沙床面沙坝的动力特性。结果表明：沙床沙坝的形态随时间变化，并不趋于平衡状态;通过对现有沙坝-平床过渡过程弱非线性稳定性分析的重新审视，提出了一种新的沙坝-平床过渡过程弱非线性稳定性分析模型，该模型适当考虑了Froude数与Shields数之间的函数关系。结果表明，在平均床面坡度较小、流速系数较大的范围内，沙滩转换过程表现为亚临界分岔。此外，Izumi将现有的通道起始模型扩展到更一般的情况，其中基态斜率轮廓是任意给定的。分析表明，渠道的间距约为坡面水流深度的1000倍。

项目成果

VALIDATION OF A NUMERICAL MODEL FOR FLOW AND BEDFORM DYNAMICS

流动和床形动力学数值模型的验证

• 发表时间: 2007
• 期刊: 水工学論文集 第51巻
• 作者: Sanjay Giri;Yasuyuki SHIMIZU
• 通讯作者: Yasuyuki SHIMIZU

Geometric Characteristics of bats on layers with rocks or cohesive material

岩石或粘性材料层上蝙蝠的几何特征

• 发表时间: 2007
• 期刊: River Sedimentation 10(印刷中)
• 作者: 山口里実;泉 典洋;泉 典洋;Hiroshi Takebayashi;Hiroshi Takebayashi
• 通讯作者: Hiroshi Takebayashi

Weakly nonlinear stability analysis of fluvial dunes by the use of the mixing length turbulent model

基于混合长度湍流模型的河流沙丘弱非线性稳定性分析

• 发表时间: 2007
• 期刊: Annual Journal of Hydraulic Engineering Vol.50
• 作者: Izumi;N.
• 通讯作者: N.

Analysis of stream channel geometry and physiographic formative process in valley flats

河谷滩地河道几何形状及地貌形成过程分析

• 发表时间: 2007
• 期刊: Annual Journal of hydraulic engineering, JSCE vol.51
• 作者: Nogami;T.;Watanabe;Y.;Yasuda;H.;Hasegawa;K.
• 通讯作者: K.

初期河床に与える微小擾乱が砂州の発達及び砂州形状に及ぼす影響について

初始河床微扰动对沙洲发育及形态的影响

• 发表时间: 2007
• 期刊: 水工学論文集 第51巻
• 作者: 小林健介;清水康行;Sanjay Giri;渡邊康玄
• 通讯作者: 渡邊康玄