Estimation of key parameters in model for solute transport in rivers and streams

The exchange mechanisms associated with transient storage zones of a natural heterogeneous environment are often modified by unsteady water flux in the transient storage zone. This phenomenon can play an important role in the mass exchange between the free flowing water zone and the transient storage zones and may be the cause of the plateau region of the tail of observed concentration curves in natural streams. Deterministic interpretation methods are often used to generate the shape of the solute concentration curves in natural streams based on representations of transient storage exchange. Although many models are available to predict the parameters for the deterministic interpretation method, none can be used with confidence unless previously calibrated in the particular river reach under consideration. Therefore, the availability of reliable means for the provision of these parameters is usually the primary difficulty in the prediction of the rate of movement, dilution, and mixing of solute in rivers and streams. Measured tracer-response curves produced from the injection of a known quantity of soluble tracer provide one means for obtaining the requisite parameters. In this work, we advance an alternative approach based on the use of hydraulic and geometric information that are easily obtained in natural streams. Empirical equations used to predict the parameters are also analyzed to evaluate their behavior in representing solute mixing in natural streams with transient storage zones. Finally, the present proposals are validated against field meausrements of the solute concentration curves of chloride along a 1.2~km reach of the Shingobee River, Minnesota, U.S.A.     

开敞式高比转速轴流泵模型装置的试验研究

提出了高比转速轴流泵模型设计的一些新的处理方法,介绍了开敞式轴流泵结构型式的特点、流道的设计及其模型装置的试验研究。结果表明：该模型装置过流量大,装置效率高,高效范围广,可以在很广的低扬程范围内推广应用。     

一种特定堰型的淹没出流流量计算经验公式研究

对特定堰型的淹没出流,因流量系数、侧收缩系数及淹没系数的不确定性,难以利用经验系数推算溢流堰的过流量。该文提出一种特定堰型下淹没出流流量推演的精确方法：基于物理模型试验数据,对堰上水头与堰下游相对水位进行相关分析,得到特定流量下其相关关系式;后以此关系式中的参数与流量进行二次相关分析,最终得到流量-堰上水头-堰下游相对水位的关系式。经试验验证表明,所得关系式精度较高,其分析方法可应用于类似的多因次相关分析中。     

简易地下水模型EasyGWM在南水北调中线受水区的应用

为对南水北调中线受水区(下简称中线受水区)的地下水资源进行有效模拟,研制简易地下水模型EasyGWM(Easy Groundwater Model),并以2002年-2003年的区域地下水动态资料进行模型验证,对EasyGWM模型和MODFLOW在中线受水区的模拟结果的对比分析表明,当研究时空尺度较大时,相比建模复杂、资料难于获取且运算耗时的MODFLOW模型,EasyGWM模型不仅能取得与实际资料相适应的模拟精度,还能节省模型建模及运算时间。     

Numerical and experimental turbulence studies on shallow open channel flows

The standard shallow water equations (SWEs) model has been proven to be insufficient to consider the flow turbulence due to its simplified Reynolds-averaged form. In this study, the k-ε model was used to improve the ability of the SWEs model to capture the flow turbulence. In terms of the numerical source terms modelling, the combined SWEs k-ε model was improved by a recently proposed surface gradient upwind method (SGUM) to facilitate the extra turbulent kinetic energy (TKE) source terms in the simulation. The laboratory experiments on both the smooth and rough bed flows were also conducted under the uniform and non-uniform flow conditions for the validation of the proposed numerical model. The numerical simulations were compared with the measured data in the flow velocity, TKE and power spectrum. In the power spectrum comparisons, a well-studied Kolmogorov's rule was also employed to complement both the numerical and experimental results and to demonstrate that the energy cascade trend was well-held in the investigated flows.     

高速水流水力特性原型观测的涂层痕迹法初探

对常规原型观测的方法和技术进行了评述,指出高速水流特性原型观测存在的一些难点与不足,提出用新的涂层痕迹法进行高速水流水力特性原型观测的基本原理和技术方法,并结合室内试验研究和在工程中的初步应用,论述了这种方法技术的可行性。同时还探讨了该方法技术进一步研究的内容和技术路线,展望了应用前景。