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Analytical solutions of turbulent boundary layer beneath forward-leaning waves

Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 695-710页

作者： Yiqin XIE Jifu ZHOU Xu WANG Jinlong DUAN yongjun lu Shouqian LI Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100038China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research InstituteNanjing 210024China

As a typical nonlinear wave,forward-leaning waves can be frequently encountered in the near-shore areas,which can impact coastal sediment transport ***,it is of significance to describe the characteristics of the boundary layer beneath forward-leaning waves accurately,especially for the turbulent boundary *** this work,the linearized turbulent boundary layer model with a linear turbulent viscosity coefficient is applied,and the novel expression of the near-bed orbital velocity that has been worked out by the authors for forward-leaning waves of arbitrary forward-leaning degrees is further used to specify the free stream boundary condition of the bottom boundary ***,a variable transformation is found so as to make the equation of the turbulent boundary layer model be solved analytically through a modified Bessel ***,an explicit analytical solution of the turbulent boundary layer beneath forward-leaning waves is derived by means of variable separation and variable *** analytical solutions of the velocity profile and bottom shear stress of the turbulent boundary layer beneath forward-leaning waves are verified by comparing the present analytical results with typical experimental data available in the previous literature.

关键词： forward-leaning wave turbulent boundary layer velocity profile bottom shear stress

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软体排沉排水流结构与排体动力特性数值模拟

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哈尔滨工程大学学报 2024年第5期45卷 1013-1023页

作者：杨涵苑陆永军左利钦陆彦南京水利科学研究院水灾害防御全国重点实验室江苏南京210029 武汉大学水资源工程与调度全国重点实验室湖北武汉430072

针对软体排沉排施工时容易出现撕排和断排的问题,本文基于k-ωSST湍流模型,采用分区耦合算法对顺水沉排过程进行双向流固耦合模拟。分析了不同水流条件下绕流流场、涡流结构与排体动力特性,并结合室内水槽试验验证模型计算精度。结果表... 详细信息

针对软体排沉排施工时容易出现撕排和断排的问题,本文基于k-ωSST湍流模型,采用分区耦合算法对顺水沉排过程进行双向流固耦合模拟。分析了不同水流条件下绕流流场、涡流结构与排体动力特性,并结合室内水槽试验验证模型计算精度。结果表明:水流流经排体后发生流动分离,导致沿排宽中轴线形成对称的回流区。排体迎水面流速随水深增加呈指数型递增,排体后方高速尾流带的最大流速相较平均流速可增大40%~50%。当雷诺数增加,主体涡流结构由靠近床面侧逐步向水面处发展。此外,排体所受应力沿横向呈条带状分布,峰值集中于排体与翻板交界处及排头梁附近。研究结果可为完善排体结构设计、改进沉排施工工艺提供理论指导。

关键词：航道整治软体排护岸工程流固耦合沉排动力响应流场特性涡流结构

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山区河流宽级配泥沙生态环境效应研究进展

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应用基础与工程科学学报 2024年第2期32卷 442-460页

作者：袁隆湖陆永军刘怀湘周雄冬陆彦水利部交通运输部国家能源局南京水利科学研究院江苏南京210029 长江保护与绿色发展研究院江苏南京210029 清华大学水沙科学与水利水电工程国家重点实验室北京100084

泥沙是影响河流生态环境的主要因素之一,其生态环境效应对维持水环境平衡和水生生物多样性发挥重要作用.宽级配泥沙是山区河流河床组成的主要类型,与平原河流级配较窄的泥沙相比具有独特的生态环境效应.加之山区河流中大规模梯级水库建... 详细信息

泥沙是影响河流生态环境的主要因素之一,其生态环境效应对维持水环境平衡和水生生物多样性发挥重要作用.宽级配泥沙是山区河流河床组成的主要类型,与平原河流级配较窄的泥沙相比具有独特的生态环境效应.加之山区河流中大规模梯级水库建设运行等人类活动愈加强烈,宽级配泥沙的生态环境效应问题进一步复杂化.系统梳理了山区河流宽级配泥沙在污染物吸附、解吸和输移等方面的环境效应,以及对水生微生物、动植物的生态效应,分析了梯级水库影响下山区河流宽级配泥沙的生态环境效应变化,探讨了目前研究中存在的问题,并对研究前景进行展望,以期为山区河流生态环境保护提供参考.

关键词：山区河流梯级水库宽级配泥沙生态环境效应吸附/解吸水生生物

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基于改进的独立分量分析混叠通信信号盲分离

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现代防御技术 2024年第3期52卷 87-95页

作者：韩树楠陈铸龙卢勇君空军航空大学吉林长春130000 中国人民解放军93107部队辽宁沈阳110000 中国人民解放军95507部队贵州贵阳550000

针对时域与频域均交叠的多路数字带通通信信号盲分离问题,利用布谷鸟搜索算法,研究了一种新的基于独立成分分析的盲分离方法。在均匀线阵下,构建混叠信号模型;从最大化信号非高斯性角度,将盲源分离问题转化为信号峭度的优化问题;利用布... 详细信息

针对时域与频域均交叠的多路数字带通通信信号盲分离问题,利用布谷鸟搜索算法,研究了一种新的基于独立成分分析的盲分离方法。在均匀线阵下,构建混叠信号模型;从最大化信号非高斯性角度,将盲源分离问题转化为信号峭度的优化问题;利用布谷鸟搜索算法优化求解近似峭度的代价函数,将迭代产生的适应度值最高的个体作为解混向量,实现源信号的分离。与已有的基于固定点算法的独立成分分析方法相比,该方法能够克服其无法分离时频域混叠的振幅键控(ASK)信号的限制,适用于任何调制类型的数字带通通信信号盲分离。通过仿真实验验证了方法的有效性并分析了方法性能,实验结果表明在较低信噪比条件下,分离的信号具有较高信干比,说明方法具有较高的鲁棒性。

关键词：独立成分分析布谷鸟搜索通信信号时频域混叠盲分离

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水流冲刷作用下软体排守护边滩失稳机理概化模型试验初步研究

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应用基础与工程科学学报 2024年第3期32卷 773-786页

作者：魏祥龙戴佳琦左利钦陆永军杨涵苑陆彦黄廷杰芦安平袁赛瑜河海大学水灾害防御全国重点实验室江苏南京210024 南京水利科学研究院水灾害防御全国重点实验室江苏南京210029 四川大学山区河流保护与治理全国重点实验室四川成都610065 水利部南京水利水文自动化研究所江苏南京210012 长江保护与绿色发展研究院江苏南京210024 长江南京航道工程局江苏南京210011

软体排是河道与航道整治工程中广泛应用的洲滩守护结构,排体所护边滩的稳定性对排体变形及服役状态具有重要影响.水流作用下的边滩局部动力环境复杂,其失稳模式与水下自由边坡模式不同,失稳模式及产生机理有待探究.基于概化物理模型试验... 详细信息

软体排是河道与航道整治工程中广泛应用的洲滩守护结构,排体所护边滩的稳定性对排体变形及服役状态具有重要影响.水流作用下的边滩局部动力环境复杂,其失稳模式与水下自由边坡模式不同,失稳模式及产生机理有待探究.基于概化物理模型试验,对排体守护下的边滩失稳模式及形成机理开展研究.研究表明,排体守护边滩会发生牵引型与滑覆型两种失稳形式,边滩牵引型失稳所引起的排体应变响应较小,发生在排体整个冲刷周期.排尾冲刷变形累计达到一定程度后会产生偶发性的滑覆型失稳,引起边滩产生大范围滑动失稳及排体大范围沉降变形;排体守护下边滩滑覆型失稳的机理:水流冲刷引起边滩潜在滑动面下移,随边缘冲刷深度的增加,潜在滑动面与水平面的夹角不断增大,稳定性不断降低,最终导致潜在滑动面力学失稳(F_(s)<1),引起内部边滩产生大范围的滑覆型失稳.

关键词：软体排航道整治洲滩守护崩岸失稳机理光纤传感稳定性分析

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FLOW MECHANISM AND VELOCITY FIELD NEAR GROIN-LIKE STRUCTURES

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China Ocean Engineering 1989年第2期4卷 203-216页

作者： lu, yongjun Zhou, Yaoting Hohai Univ China

The flow mechanism near the groin-like structure and two-dimensional model are presented in this paper. The velocity distribution behind the groin-like structure is found to be self-preserving in character. Hence, the Reynolds equations can be transformed into an ordinary differental equation by similarity and the equation of velocity distribution behind the groin-like structure is obtained. The calculated results are in a good agreement with experimental ones. In addition, the turbulent viscosity along the main flow direction is briefly discussed.

关键词： Equations of Motion Mathematical Models

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天然橡胶/三元乙丙橡胶并用胶辐射交联制备及其耐热空气老化性能

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辐射研究与辐射工艺学报 2024年第3期42卷 55-62页

作者：石勇程安仁代培矫阳陆永俊郭月莹海军装备部驻北京地区第七军事代表室北京100071 北京市射线应用研究中心有限公司/辐射新材料北京市重点实验室北京100015 北京陕煤高新技术研究院有限公司北京100095

针对天然橡胶(NR)/三元乙丙橡胶(EPDM)并用胶共混效果不佳和耐老化性能较差的问题,本研究采用辐射交联技术制备了天然橡胶/三元乙丙橡胶并用胶,通过与热交联制备的并用胶对比,明确了辐射交联工艺对共混效果的促进作用。重点分析了NR/EPD... 详细信息

针对天然橡胶(NR)/三元乙丙橡胶(EPDM)并用胶共混效果不佳和耐老化性能较差的问题,本研究采用辐射交联技术制备了天然橡胶/三元乙丙橡胶并用胶,通过与热交联制备的并用胶对比,明确了辐射交联工艺对共混效果的促进作用。重点分析了NR/EPDM共混胶中生胶并用比和辐射交联等因素对老化前后并用胶力学性能的影响规律。热空气老化前,随着EPDM占比的增大,热交联样品的初始拉伸强度和伸长率曲线呈先降低后上升趋势,而辐射交联样品初始拉伸强度和伸长率呈线性下降趋势,说明辐照处理改善了EPDM/NR并用胶初始力学性能,辐射交联提高了NR和EPDM分子之间交联结构的完善性。热空气老化后,辐射交联样品的性能下降幅度小于热交联的样品,说明在热交联基础上,引入辐射技术可以提升辐射交联样品热老化后的伸长率保持率,尤其是在NR占比较大的情况下,辐射样品性能下降幅度能减小约50%。由此说明,利用辐射交联技术制备天然橡胶/三元乙丙橡胶并用胶具有比传统热硫化交联具有更好的耐热空气老化性能。

关键词：辐射交联天然橡胶三元乙丙橡胶热空气老化硫化剂辐射硫化

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Geochemical and microbial characters of sediment from the gas hydrate area in the Taixinan Basin, South China Sea

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Acta Oceanologica Sinica 2017年第9期36卷 52-64页

作者： GONG Junli SUN Xiaoming LIN Zhiyong lu Hongfeng lu yongjun School of Earth Science and Engineering Sun Yat-sen University Guangzhou 510275 China School of Marine Sciences Sun Yat-sen University Guangzhou 510006 China Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering Guangzhou 510006 China Guangzhou Marine Geology Survey Guangzhou 510075 China School of Life Sciences Sun Yat-sen University Guangzhou 510275 China

The Taixinan Basin is one of the most potential gas hydrate bearing areas in the South China Sea and abundant gas hydrates have been discovered during expedition in 2013. In this study, geochemical and microbial methods are combinedly used to characterize the sediments from a shallow piston Core DH_CL_11（gas hydrate free） and a gas hydrate-bearing drilling Core GMGS2-16 in this basin. Geochemical analyses indicate that anaerobic oxidation of methane（AOM） which is speculated to be linked to the ongoing gas hydrate dissociation is taking place in Core DH_CL_11 at deep. For Core GMGS2-16, AOM related to past episodes of methane seepage are suggested to dominate during its diagenetic process; while the relatively enriched δ18O bulk-sediment values indicate that methane involved in AOM might be released from the ＂episodic dissociation＂ of gas *** analyses indicate that the predominant phyla in the bacterial communities are Firmicutes and Proteobacteria（Gammaproteobacteria and Epsilonproteobacteria）, while the dominant taxa in the archaeal communities are Marine_Benthic_Group_B（MBGB）, Halobacteria, Thermoplasmata, Methanobacteria,Methanomicrobia, Group C3 and MCG. Under parallel experimental operations, comparable dominant members（Firmicutes and MBGB） are found in the piston Core DH_CL_11 and the near surface layer of the long drilling Core GMGS2-16. Moreover, these members have been found predominant in other known gas hydrate bearing cores, and the dominant of MBGB has even been found significantly related to gas hydrate occurrence. Therefore,a high possibility for the existing of gas hydrate underlying Core DH_CL_11 is inferred, which is consistent with the geochemical analyses. In all, combined geochemical and microbiological analyses are more informative in characterizing sediments from gas hydrate-associated areas in the South China Sea.

关键词： Geochemistry Microbial community 16S rRNA Gas hydrate Taixinan Basin South China Sea

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Process-based suspended sediment carrying capacity of silt-sand sediment in wave conditions

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International Journal of Sediment Research 2022年第2期37卷 229-237页

作者： Liqin Zuo Dano Roelvink yongjun lu Guanghui Dong State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research Institute Changjiang Nanjing Waterway Engineering Bureau

The sediment carrying capacity is one of the fundamental issues in sediment *** is of great importance both in theory and practice to develop process-based approaches for the sediment carrying capacity for a wider range of silt-sand *** current study focuses on the approach for depth-averaged concentration of silt-sand sediment under non-breaking wave *** integrating process-based suspended sediment concentration(SSC) profiles,new synthetic expressions for depth-averaged SSC for vortex rippled beds and sheet flow conditions were *** proposed expressions involve several basic physical processes,including the effects of bed forms,stratification,hindered settling,mobile bed,etc.A number of experimental datasets were collected for verification and reasonable results were *** were made on the changes of sediment concentration under increasing wave dynamics conditions,which show that the proposed formulas can describe the phenomenon which has been observed in experimental tests that SSC does not always increase when wave dynamics increase due to the effects of bed *** short,the current research provides a process-based approach for wave-induced sediment carrying capacity,which is expected to be applicable for numerical modeling and engineering practice.

关键词： Sediment carrying capacity Silt sediment Wave-induced sediment concentration Depth-averaged equilibrium concentration Process-based

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Modelling of cantilever bank failure for peat-type meander bends in the source region of the Yellow River

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International Journal of Sediment Research 2023年第3期38卷 421-431页

作者： Hanyuan Yang Zhiwei Li yongjun lu Huaixiang Liu Liqin Zuo State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research Institute Yangtze Institute for Conservation and Development

Bank retreat involving a combination of fluvial erosion and bank collapse has been found to be a major contributor to sediment transport, lateral migration, and planform evolution of meandering *** studies have largely examined the general mechanism of cantilever bank failure. However, the composite process of beam(toppling) failure caused by shear failure of the lower part composed of noncohesive soil remains poorly understood. The current paper investigates the diversity and coupling of this collapse process, which is the dominant pattern in the peat-type meandering rivers of the Zoige River basin in the source region of the Yellow River. For this purpose, morphologic and hydraulic measurements were done in the summers of 2016 and 2017. Moreover, a combined method of a theoretical model and numerical simulation was developed to be applied for a continuous meandering channel in the Zoige basin, focusing in particular on five typical cross sections of a highly convoluted bend approaching neck cutoff. Specifically, the theoretical model evaluating the stability of overhanging riverbank was based on static equilibrium theory considering the interaction between composite soil layers. In addition, the Bank Stability and Toe Erosion Model was used to simulate the retreat process of the silt layer based on field measurements including bank morphology, soil composition, and hydrological parameters. Thus, a calculation method for the occurrence of cantilever beam failure in the flood period is proposed, and temporal change and spatial variability in bank profiles caused by three consecutive failures is estimated at the five sections. Satisfactory results showed a relatively close agreement between the calculations and field measurements in terms of the width of the overhanging arms and the dimensions of the slump blocks.

关键词： River bends Bank erosion Cantilever failure Numerical simulation Meandering river

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