Delineating Capture Zone of a Pumping Well in a Slanting Regional Groundwater Flow to a Stream with a Leaky Layer

In this study, analytical and semi-analytical solutions are derived to delineate capture zone of a pumping well near a stream where a leaky layer exists between the aquifer and the stream. A groundwater regional flow is considered in the aquifer and allowed to have different angles with respect to the stream axis. Three critical pumping rates are introduced. At the first pumping rate, capture zone boundary tangents the interface between the aquifer and the leaky layer; called the in-homogeneity boundary. At the second pumping rate, capture zone boundary tangents the stream boundary and if the rate is increased, a part of pumped water would be withdrawn from the stream. The third pumping rate, which may be smaller or larger than the other two, is defined as the rate at which stream water begins to enter the leaky layer; it may or may not be captured by the pumping well. Four different capture zone configurations (cases) are analyzed for different values of pumping rates, groundwater flow directions, and leaky layer’s thickness and hydraulic conductivity. The first three cases analyze hydraulic situations whereby capture zone does not reach the stream, and hence, no pumped water is withdrawn from the stream. With the lowest pumping rate in the first case, no stream water enters the leaky layer. It enters the leaky layer but not the aquifer in the second, and enters the leaky layer and the aquifer in the third case. In the fourth case, where capture zone boundary intersects the stream, the fraction of pumped stream water to total pumped water is delineated.     

When does a stream become a river?

The distinction between a “stream” and “river” is imprecise and vague despite the popular usage of the terms across disciplines for describing flowing waterbodies. Based on an analysis of named flowing waterbodies in the continental United States, we suggest a bank-to-bank channel width of 15 m as a working threshold in defining smaller “streams” from larger “rivers.”     

台阶形陆架上孤立波传播的数值模拟

为了研究孤立波在带有陡升台地的陆架上的传播,用MAC方法求解了二维纳维尔-斯托克斯方程。本文在以下几点,改进了东京大学提出的修正的网格标记法:1.给出交错网格的新的标号系统;2.推导出自由表面上非规则星的新的压力迭代公式;3.对流函数、压力和速度使用了三值悬旗;4.把一维Burgers方程的部分守恒形式扩展用于二维N-S方程。这些使得程序更简单和精确。计算结果证卖,物理上很好地解释了孤立波的传播,入射波分成了反射波和透射波,然后开始分裂、破碎。 本文计算结果与线性波理论的结果很一致,但后者不能给出波运动的过程。     

Construction of a temporary protective embankment for eliminating a failure of a sewer inverted siphon

Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 9, pp. 16–19, September, 1991.     

Retrofitting a stormwater retention pond using a deflector island

Stormwater retention ponds are one of the principal methods to treat stormwater runoff. Analysis of residence time distribution (RTD) curves can be used to evaluate the capability of these ponds for sediment removal. Deflector islands have been suggested as a means of improving the performance of retention ponds, due to their diffusing the inlet jet. In this study, the effect of an island on retention pond performance was investigated using a physical model of an existing stormwater retention pond. The physical model is a trapezoidal pond having top dimensions 4.1 x 1.5 x 0.23 m and side slopes of 2:1 (h:v). Three different arrangements were studied. The results show that placing an island to deflect the influent to a stormwater retention pond does not improve pond performance, rather it stimulates short-circuiting. This unexpected behaviour, in relation to previous studies, is considered to be a consequence of the model pond incorporating sloping walls; which is a novel aspect of this paper.     

大尺度圆柱周围的波流场的耦合计算

本文利用波浪弥散关系的迭代计算求得波向与流向的夹角，并用有限元法求解含流的缓坡方程，得到在缓变地形和定常流场共同影响下的大尺度圆柱周围的波流场的耦合解。     

新型隔壁式高压岔管结构研究

通过对新型分岔结构－隔壁式岔管的研究，认真分析其体形设计、力学试验和结构有限元计算成果，发现这种新型分岔管在布置、结构和水力学方面较普通的“Y”型和“卜、形岔管具有一定的优势，其分岔灵活，结构对称无缺省，承爱内、外水压力能力强，双向过流条件好，具有广阔的应用前景，比较适合于抽水蓄能电站中的高水头、大直径、深埋藏的岔管的运用要求。     

Non-spherical multi-oscillations of a bubble in a compressible liquid

Bubble dynamics are associated with wide and important applications in cavitation erosion in many industrial systems, medical ultrasonics and underwater explosions. Two recent developments to this classical problem are reviewed in this paper. Firstly, computational studies on the problem have commonly been based on an incompressible fluid model. However, a bubble usually undergoes significantly damped oscillation due to the compressible effects. We model this phenomenon using weakly compressible theory and a modified boundary integral method. This model considers the energy loss due to shock waves emitted at minimum bubble volumes. Secondly, the computational studies so far have largely been concerned with the first-cycle of oscillation. However, a bubble usually oscillates for a few cycles before it breaks into much smaller ones. We model both the first- and second-cycles of oscillationand predict damped oscillations. Our computations correlate well with the experimental data.     

Effect of a free surface on the formation of a wave bed of a channel flow

Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 5, pp. 50–52, May, 1989.