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国家自然科学基金(11372232)

作品数:7 被引量:37H指数:4
相关作者:槐文信杨中华赵芳李成光曾玉红更多>>
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Numerical investigation of flow through vegetated multi-stage compound channel被引量:8
2014年
This paper addresses the problem of the renormalization group k turbulence modeling of a vegetated multi-stage compound channel. Results from Micro acoustic Doppler velocimeter(ADV) tests are used with time and spatial averaging(doubleaveraging method) in the analysis of the flow field and the characterization. Comparisons of the mean velocity, the Reynolds stress, and the turbulent energy distribution show the validity of the computational method. The mean velocity profile sees an obvious deceleration in the terraces because of vegetation. Secondary flow exists mainly at the junction of the main channel and the vegetation region on the first terrace. The bed shear stress in the main channel is much greater than that in the terraces. The difference of the bed shear stress between two terraces is insignificant, and the presence of vegetation can effectively reduce the bed shear stress.
王雯槐文信高猛
关键词:VEGETATION
刚性淹没球冠状植被水流特性试验研究被引量:10
2018年
本文将植被体型概化为由球状树冠和主干组成的树状植被,采用Micro ADV测量了树状植被影响下明渠水流的流速分布,分析了不同流量和水深条件下4组树状植被对明渠水流的影响,着重研究了树状刚性植被水流的平均流动和紊动结构,比较了多个典型位置处水流的纵向流速、垂向流速以及紊动强度。试验结果表明,水深越小,无量纲纵向流速越大;树冠的形状对水流特性的影响较大,在树状植被附近,纵向流速的垂向分布在树干层近似均匀分布,在树冠层先减小后增大,在无植被层符合对数分布;紊动强度在树冠层较大,在树干层和无植被层较小;通过象限分析,发现下扫作用主要在植被层起主导作用,喷射作用主要在自由水层占主导。
赵芳Aristotelis MavrommatisAnastasios Stamou槐文信槐文信
关键词:MICROADV紊动结构
基于唯象模型的部分植被河道流动分析
2014年
对局部有挺水植被明渠均匀流,采用分区模型,合理计入区间界面的表观切应力,建立动力平衡方程,推导出各区的断面平均纵向流速公式.基于唯象模型得出了植被区和非植被区交界面上的表观切应力,该应力是由界面上引起动量交换且占主导地位的漩涡产生的.用动量差表征表观切应力,其动量交换系数与占主导地位的漩涡半径和断面水力半径之比的1/3次方成正比.最后将计算结果与实测值进行比较,两者符合良好,表明本文模型可有效用于局部有挺水植被明渠均匀流的水流计算.
罗婧槐文信
关键词:明渠流动植被流速
强弯河道水流结构及离散特性研究被引量:5
2014年
对180°强弯河道水流结构及离散特性进行了研究.采用三维多普勒超声流速仪(ADV)对强弯河道5个典型断面的流速场进行了量测,得到了各典型断面上的实测流速资料;进而采用改进的分区模型,分别对强弯河道的横向和纵向离散系数进行了研究.结果表明:在弯道进口段,凹岸附近水流受到限制,流速减小,凸岸附近水流流速增大,纵向剪切流速较大,故纵向离散系数较大,此时二次流尚未形成,横向掺混并不剧烈,所以横向离散系数还比较小.随着水流入弯的不断发展,弯道内二次流逐渐形成并不断增强,最大流速逐渐向凹岸转移,此时横向剪切逐渐增强,横向离散系数逐渐增大;而纵向剪切趋于平缓,纵向离散系数逐渐减小.在弯顶附近,二次流得到充分发展,横向离散系数达到最大值.在弯道下游段,二次流强度逐渐减弱,横向剪切流速减小,使得横向离散系数逐渐减小,此时最大流速转移到凹岸附近,流速分布变化趋于平缓,纵向剪切流速变化幅度较小,纵向离散系数基本趋于稳定.
李成光槐文信曾玉红杨中华
关键词:二次流纵向离散系数
明渠植被水流水动力学特性
水生植被是生态河道系统中的重要组成部分,其存在形式对水流的水动力学特性有着很重要的影响。根据水生植被在明渠水流中的存在形式,可以将其分为漂浮植被和沉水植被;根据植被群落的高度是否唯一,可以将其分为单层植被和多层植被。植被...
槐文信王伟杰
关键词:流速分布沉水植被
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Effect of vegetation on flow structure and dispersion in strongly curved channels被引量:13
2015年
The effect of vegetation on the flow structure and the dispersion in a 180 o curved open channel is studied. The Micro ADV is used to measure the flow velocities both in the vegetation cases and the non-vegetation case. It is shown that the velocities in the vegetation area are much smaller than those in the non-vegetation area and a large velocity gradient is generated between the vegetation area and the non-vegetation area. The transverse and longitudinal dispersion coefficients are analyzed based on the experimental data by using the modified N- zone models. It is shown that the effect of the vegetation on the transverse dispersion coefficient is small, involving only changes of a small magnitude, however, since the primary velocities become much more inhomogeneous with the presence of the vegetation, the longitudinal dispersion coefficients are much larger than those in the non-vegetation case.
李成光薛万云槐文信
关键词:VEGETATION
Prediction of velocity distribution in straight open-channel flow with partial vegetation by singular perturbation method被引量:2
2016年
A numerical analysis model based on two-dimensional shallow water differential equations is presented for straight open-channel flow with partial vegetation across the channel. Both the drag force acting on vegetation and the momentum exchange between the vegetation and non-vegetation zones are considered. The depth-averaged streamwise velocity is solved by the singular perturbation method, while the Reynolds stress is calculated based on the results of the streamwise velocity. Comparisons with the experimental data indicate that the accuracy of prediction is significantly improved by introducing a term for the secondary current in the model. A sensitivity analysis shows that a sound choice of the secondary current intensity coefficient is important for an accurate prediction of the depth-averaged streamwise velocity near the vegetation and non-vegetation interfaces, and the drag force coefficient is crucial for predictions in the vegetation zone.
Wenxin HUAISuwen SONGJie HANYuhong ZENG
Two timescales for longitudinal dispersion in a laminar open-channel flow
2017年
At small dimensionless timescales T(= tD/H^2), where t is the time, H is the depth of the channel and D is the molecular diffusion coefficient, the mean transverse concentration along the longitudinal direction is not in a Gaussian distribution and the transverse concentration distribution is nonuniform. However, previous studies found different dimensionless timescales in the early stage, which is not verified experimentally due to the demanding experimental requirements. In this letter, a stochastic method is employed to simulate the early stage of the longitudinal transport when the Peclet number is large. It is shown that the timescale for the transverse distribution to approach uniformity is T= 0.5, which is also the timescale for the dimensionless temporal longitudinal dispersion coefficient to reach its asymptotic value, the timescale for the longitudinal distribution to approach a Gaussian distribution is T= 1.0, which is also the timescale for the dimensionless history mean longitudinal dispersion coefficient to reach its asymptotic value.
王宇飞槐文信杨中华季斌
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