The fractal characteristic change in the Huanghe River Estuary due to the hydrodynamic conditions’variation

The study area lies in the subaqueous delta, which came into being in 1964 - 1976. Oneoil-field road has been built for exploring petroleum to form a wave barrier. The hydrodynarnic conditions on the north side of the road are relatively violent, on the contrary the hydrodynarnic conditions on the south side of the road are nearly placid. This makes the study area a natural laboratory for studying the influence of the hydrodynarnic conditions on the fractal characteristics of the tidal flat. Selecting an area is named Case Ⅰ on the side of stronger hydrodynarnic activities and an area is named Case Ⅱ on the other side. Measuring the topography and sampling and analyzing the granulometrical composition, it is found that the hydrodynarnic conditions have fatal influence on the surface fractal dimensions and the granulometrical fractal dimensions of the area. In Case Ⅰ , which has strong hydrodynarnic conditions, the surface fractal dimensions are obviously larger than those of Case Ⅱ , and the granulometrical fractal dimensions are relatively smaller than those of Case Ⅱ , the surface fractal dimensions of Case Ⅰ decrease quickly with the increase of grid size; the granulometrical fractal dimensions are disperse, while the hydrodynarnic conditions of Case Ⅱ are just reverse. A sampling line and a core sampling on each side of the road are selected. It is found that on the south side of the road the granulometrical fractal dimensions vary regularly in the line and with the depth, the farther apart from the road, the smaller the fractal dimensions, and the deeper the sampling position the larger the fractal dimensions, while granulometrical fractal dimensions on the north side of the road have no such regularity pattern. The mechanism of the influence of the hydrodynarnic conditions on the fractal characteristics is discussed.

Tidal flat erosion of the Huanghe River Delta due to local changes in hydrodynamic conditions

An ideal nature system for the study of post-depositional submarine mass changing under wave loading was selected in the intertidal platform of the subaqueous Huanghe River Delta, a delta formed during period from 1964 to 1976 as the Huanghe River discharged into the Bohai Gulf by Diaokou distributary. A road embankment constructed for petroleum recovery on the inter-tidal platform in 1995 induced the essential varieties of hydrodynamic conditions on the both sides of the road. With both sides sharing similarities in （1） initial sedimentary environment, （2） energetic wave loading, （3） differential hydrodynamic conditions in later stages, （4） enough long-range action, and （5） extreme shallow water inter-tidal platforms; the study is representative and feasible as well. Two study sites were selected on each side of the road, and a series of measurements, samplings, laboratory experiments have been carried out, including morphometry, hydrodynamic conditions, sediment properties, granularity composition, and fractal dimension calculation of the topography in the two adjacent areas. It was observed that in the outer zone, where wave loading with high magnitude prevailed, the tidal flat was bumpy and exhibited a high erosion rate and high fractal dimension. Further, the fractal dimension diminished quickly, keeping with the enlarging of calculative square size. However in the inner zone, where the hydrodynamic condition was weak, the tidal fiat was fiat and exhibited a low erosion rate and low fractal dimensions; the fractal dimension diminished with the enlarging of calcu- lative square size. The fractal dimensions in the different hydrodynamic areas equalized increasingly as the calculative square size accreted to threshold, indicating that the hydrodynamic condition plays a significant role in topography construction and submarine delta erosion process. Additionally, the later differentiation of sediment properties, granularity composition, microstructure characteristics, and mineral composition induced by the different hydrodynamic conditions can also contribute to the variation of topography and sea-bed erosion in the two adjacent areas.

Numerical investigation of hydrodynamic tractor-retarder assembly under traction work condition

To obtain the performance characteristics of hydrodynamic tractor-retarder assembly under traction work condition,a numerical simulation model of flow channel was established and tetrahedron unstructured grids were adopted in the meshing stage.The racing rotating speed of the brake wheels was calculated by computational fluid dynamics（CFD） calculation and interpolation,and then accurate boundary condition was applied to the CFD simulation to study the pressure and velocity distribution of internal flow field in hydrodynamic tractor-retarder assembly.Finally,the original characteristics were calculated by CFD post-processing analysis.Comparison of experimental data and flow field analysis results showed that the calculation tolerance of the torque ratio K and the efficiency η was less than 5%,and the calculation tolerance of the pump torque coefficient λ was less than 10%.

Debris Flow Formation Process and Critical Hydrodynamic Conditions in the Meizoseismal Area of the Wenchuan Earthquake

The Wenchuan earthquake generated strong surface disturbances and triggered a large number of loose deposits, resulting in the disasterprone environment with special watershed hydrological characteristics. This paper was to propose a debris flow formation process and explore the permeability characteristics and critical hydrodynamic conditions of the loose deposits triggered by the earthquake. The Guo Juanyan gully(31°05′27″ N to 31°05′46″ N, 103°36′58″ E to 103°37′09″ E) in Du Jiangyan City, located in the meizoseismal areas of the Wenchuan earthquake, was chosen as the study area and the disaster-prone environment was analyzed. The formation process of the debris flow was first proposed using a stability analysis, and then, the permeability characteristics of loose deposits were determined via in situ permeability experiments. Finally, the critical 1 h rainfall was simulated through a distributed hydrological model and verified by field observations. The formation process of debris flow could be divided into three stages based on the relationship between the hydrodynamic force and loose deposit resistance. The critical 1 h rainfall amounts under three antecedent moisture conditions(I-dry, II-normal and III-wet) were 52 mm/h, 43 mm/h and 34 mm/h, respectively. This study proposed a debris flow formation process in the meizoseismal areas of the Wenchuan earthquake based on the stability analysis and defined the rainfall threshold for debris flow early warning at the local level, which is significant for debris flow mitigation and risk management.

Physical simulation of hydrodynamic conditions in high rank coalbed methane reservoir formation

In order to select highly productive and enriched areas of high rank coalbed methane reservoirs,based on hydrologic geology as one of the main factors controlling coalbed methane(CBM) reservoir formations,the effect of hydrodynamic forces controlling CBM reservoir formations was studied by a physical simulation experiment in which we used CBM reservoir simulation facilities.The hydrodynamic conditions of high coal rank reservoirs in the Qinshui basin were analyzed.Our experiment shows the following results:under strong hydrodynamic alternating action,δC1 of coalbed methane reservoir changed from the start at -2.95%～-3.66%,and the lightening process occurred in phases;the CH4 volume reduced from 96.35% to 12.42%;the CO2 volume decreased from 0.75% in sample 1 to 0.68% in sample 2,then rose to 1.13% in sample 3;the N2 volume changed from 2.9% in sample 1 to 86.45% in sample 3.On one hand,these changes show the complexity of CBM reservoir formation;on the other hand,they indicate that strong hydrodynamic actions have an unfavorable impact on CBM reservoir formation.It was found that the gas volume and hydrodynamic intensity were negatively correlated and low hydrodynamic flow conditions might result in highly productive and enriched areas of high rank CBM.

Experimental Study on Hydrodynamics of L-type Podded Propulsor in Straight-ahead Motion and Off-Design Conditions

试验性的测试被进行评估 L 类型 podded propulsor 的水动力学性能在直向前，用一台开水的测量仪器的运动和离开设计条件为 podded propulsors 由作者发展了，拖引坦克的一个轮船模型，并且在水粒子图象 velocimetry (PIV ) 下面测量系统。在条件的三种类型下面， L 类型 podded propulsor 的主要参数被测量，包括推进器戳和转矩，以及整个豆荚单位的戳，方面力量，和时刻。另外，在推进器和神气之间的节上的流动领域被分析。试验性的结果证明动态 azimuthing 率和方向和转弯的方向在推进器和整个豆荚单位上影响力量。因为推进器旋转的效果，力量不均匀地在左、正确的 azimuthing 方向之间被散布。这研究的调查结果为关于 L 类型 podded propulsors 的进一步的研究提供一个基础。

Hydrodynamic Efficiency Improvement of the High Skew Propeller for the Underwater Vehicle Under Surface and Submerged Conditions

An algorithm based on the Boundary Element Method(BEM)is presented for designing the High Skew Propeller(HSP)used in an Underwater Vehicle(UV).Since UVs operate under two different kinds of working conditions(i.e.surface and submerged conditions),the design of such a propeller is an unwieldy task.This is mainly due to the fact that the resistance forces as well as the vessel efficiency under these conditions are significantly different.Therefore,some factors are necessary for the design of the opti-mum propeller to utilize the power under the mentioned conditions.The design objectives of the optimum propeller are to obtain the highest possible thrust and efficiency with the minimum torque.For the current UV,the main dimensions of the propeller are pre-dicted based on the given required thrust and the defined operating conditions.These dimensions(number of blades,pitch,diameter,expanded area ratio,thickness and camber)are determined through iterative procedure.Because the propeller operates at the stern of the UV where the inflow velocity to the propeller is non-uniform,a 5-blade HSP is preferred for running the UV.Finally,the propel-ler is designed based on the numerical calculations to acquire the improved hydrodynamic efficiency.

Interferometry signatures of hydrodynamic sources with fluctuating initial conditions

We investigate the space-time evolution of the hydrodynamic particle-emitting sources with the fluctuating initial conditions generated by Heavy Ion Jet Interaction Generator(HIJING).In order to detect the event-by-event inhomogeneity of the sources,we examine the distribution of the error-inverse-weighted fluctuations,f,between the two-pion Bose-Einstein correlation functions of single and mixed events.We find that the distribution of f becomes wide for the fluctuating initial conditions.The large values of the distribution width and the root-mean-square frms are the signatures of the hydrodynamic particle-emitting sources with the fluctuating initial conditions.

Vertical 2D Modeling of Free Surface Flow with Hydrodynamic Pressure Using SIMPLE Arithmetic in σ Coordinates

A numerical model for shallow water flow has been developed based on the unsteady Reynolds-averaged Navier-Stokes equations with the hydrodynamic pressure instead of hydrostatic pressure assumption. The equations are transformed into the σ-coordinate system and the eddy viscosity is calculated with the standard k-ε turbulence model. The control volume method is used to discrete the equations, and the boundary conditions at the bed for shallow water models only include vertical diffusion terms expressed with wall functions. And the semi-implicit method for pressure linked equation arithmetic is adopted to solve the equations. The model is applied to the 2D vertical plane flow of a current over two steep-sided trenches for which experiment data are available for comparison and good agreement is obtained. And the model is used to predicting the flow in a channel with a steep-sided submerged breakwater at the bottom, and the streamline is drawn.

Numerical simulation of hydrodynamic characteristics during the diversion closure in a horizontal tunnel

Based on water inrush accident of 1841 working face of Desheng Coal Mine in Wu'an, Hebei province, China, an evaluation model of hydrodynamic characteristics of the project is set up and simulated using Matlab. It is assumed that the pipe flow would transform into seepage flow when the aggregates are plugged into the water inrush channel and the seepage flow would disappear along with grouting process. The simulation results show that the flow velocity will increase with an increase in height of aggregates accumulation body during the aggregates filling process; the maximum seepage velocity occurs on the top of plugging zone; and the water flow decreases with increasing plugging height of water inrush channel. Finally, the field construction results show that the water inrush channel can be plugged effectively by the compacted body prepared with aggregate and cement slurry.

Numerical modeling of hydrodynamic changes due to coastal reclamation projects in Xiamen Bay,China

Xiamen Bay in South China has experienced extensive coastal exploitation since the 1950s,resulting in some severe environmental problems.Local authorities now have completed or are implementing many environmental restoration projects.Evaluating the cumulative impact of exploitation and restoration activities on the environment is a complicated multi-disciplinary problem.However,hydrodynamic changes in the bay caused by such coastal projects can be characterized directly and definitively through numerical modeling.This paper assesses the cumulative effect of coastal projects on the hydrodynamic setting using a high-resolution numerical modeling method that makes use of tidal current speeds and the tidal prism as two hydrodynamic indices.Changes in tidal velocity and the characteristics of the tidal prism show that hydrodynamic conditions have declined from 1938 to 2007 in the full-tide area.The tidal current speed and tidal prism have decreased by 40% in the western part of the bay and 20% in the eastern part of the bay.Because of the linear relationship between tidal prism and area,the degraded hydrodynamic conditions are anticipated to be restored to 1972 levels following the completion of current and proposed restoration projects,i.e.33% and 15% decrease in the hydrodynamic conditions of 1938 for the western and eastern parts of the bay,respectively.The results indicate that hydrodynamic conditions can be restored to some extent with the implementation of a sustainable coastal development plan,although a full reversal of conditions is not possible.To fully assess the environmental changes in a region,more indices,e.g.,water quality and ecosystem parameters,should be considered in future evaluations.

GLOBAL WEAK SOLUTIONS TO ONE-DIMENSIONAL COMPRESSIBLE VISCOUS HYDRODYNAMIC EQUATIONS

In this article, we are concerned with the global weak solutions to the 1D com- pressible viscous hydrodynamic equations with dispersion correction δ2ρ（（φ（ρ））xxφ′（ρ））x with φ（ρ） = ρα. The model consists of viscous stabilizations because of quantum Fokker-Planck operator in the Wigner equation and is supplemented with periodic boundary and initial con- ditions. The diffusion term εuxx in the momentum equation may be interpreted as a classical conservative friction term because of particle interactions. We extend the existence result in [1] （α=1/2） to 0 〈 α ≤ 1. In addition, we perform the limit ε→0 with respect to 0 〈 α ≤1/2.

Study of the Conditions of Formation and Forecast of the Perspective Areas of Hydrogen-Sulfide Water of Surkhandarya Depression

Increase in requirement of hydrosulphuric water for improvement of the population set the task of identification of places of their possible congestion for hydrogeological service. Earlier detection of such congestions was accidental at well-drilling of different function. Therefore, development of new methodical approaches of search and allocation of perspective zones of their formation was required. It was for this purpose necessary to study in what conditions and what factors have an impact on formation of underground hydrosulphuric water. So far, definition of communication attempts only with separate geochemical signs was known. Results of studying of influence on formations of hydrosulphuric water of such factors as lithologic and facial in combination with oil-and-gas content, the geological and structural and hydrodynamic mode are given in this work. It is established that the main sign for formation of hydrosulphuric water is existence of evaporite thickness and hydrocarbon congestions. Besides, it is shown that small depth (up to 2 km) of their bedding has to be an indispensable condition and existence of explosive violation on which there has to be a water infiltration (a geological and structural factor). In the Surkhandarya region, the hydrodynamic mode caused by inclined bedding of aquifers was also one of essential factors. Active water is an exchange process with washing away (oxidation) sulfate of the containing thicknesses and subsequently, its restoration in interaction with hydrocarbons with formation of hydrosulphuric water is described. The technique is developed and the expected card of perspective zones of formation of hydrosulphuric water is constructed.

Hydrodynamic Performance of Euplectella aspergillum:Simulating Real Life Conditions in the Abyss

We detail some of the understudied aspects of the flow inside and around the Hexactinellid Sponge Euplectella aspergillum.By leveraging the flexibility of the Lattice Boltzmann Method,High Performance Computing simulations are performed to dissect the complex conditions corresponding to the actual environment at the bottom of the ocean,at depths between 100 and 1,000 m.These large-scale simulations unveil potential clues on the evolutionary adaptations of these deep-sea sponges in response to the surrounding fluid flow,and they open the path to future investigations at the interface between physics,engineering and biology.

机匣开槽控制喷水推进器不稳定流动的数值研究

针对喷水推进器小流量工况下的驼峰区不稳定流动,采用计算流体力学方法研究了其失稳特性。结果表明,随着流量的减少,推进泵的扬程和效率显著下降,扬程曲线在0.42Qd~0.8Qd范围内呈现出正斜率的驼峰特性,同时内部流场变得紊乱,并出现流动分离和回流等现象。为了改善这一不稳定流动,采用了机匣开槽技术进行流动控制,使驼峰现象得到明显改善。在最佳槽体结构参数下,深度失速工况点的扬程和效率分别比原模型提高了约147.6%和70.3%。机匣开槽一方面能够对进口来流进行整流,起到减少预旋和增大轴向进流速度的作用,另一方面可以抑制主流区漩涡的形成以及叶轮进口位置的低频压力脉动。

灰质白云岩可溶性影响研究

目的常温常压条件下方解石与白云石含量组成相近的碳酸盐岩溶蚀研究较少,为揭示此类岩石溶蚀特性,方法选取灰质白云岩作为试验对象,开展常温常压下不同酸性与流态条件下的溶蚀模拟试验,通过分析酸液pH、试样质量与孔隙变化、钙镁离子释放量等碳酸盐岩溶蚀参量,探讨影响灰质白云岩溶蚀速率的因素。结果结果表明:(1)pH≤3时,H+消耗量大于钙镁离子生成量,电导率值呈快速降低趋势;pH>3时,H+消耗量略大于钙镁离子生成量,电导率呈缓慢降低趋势,pH=3是电导率值由大变小转折的关键点,突出体现了H+消耗量与钙镁离子生成量的关系。(2)灰质白云岩方解石溶解速度与溶蚀量均远大于白云石的,初始酸液摩尔浓度较高条件下溶蚀效果更明显。(3)孔隙数量增加会加大岩石与酸溶液接触面积,进而加快岩石溶蚀速度。(4)杂质充填岩石孔隙减小了酸液对岩石的破坏。(5)高摩尔浓度酸液(pH≤3)与较强流态环境下溶蚀速率更大,岩石表面可溶物质溶出能力更强,酸液摩尔浓度较低时(pH≥4),流态变化对溶蚀速率影响较小。结论研究结果可为碳酸盐岩溶蚀研究、溶蚀程度评价与工程建设提供参考。

三峡水库支流甲烷排放研究进展

甲烷(CH_(4))对全球温室效应有着较大的贡献。三峡水库自2003年蓄水以来,其CH_(4)排放问题已受到广泛关注。但三峡水库反季节的运行方式,使支流库湾CH_(4)的产生和传输过程受到多方面的影响,进而导致其CH_(4)排放效应尚不十分明确。本文综述了三峡水库支流CH_(4)排放的研究进展,典型支流的CH_(4)排放通量普遍高于干流,位于三峡水库库尾的部分支流CH_(4)排放通量高于三峡水库库首及库中支流。大多数典型支流的CH_(4)通量在夏季均达到全年峰值,而在冬季高水位运行期均处于相对较低的水平。同时本文主要从水环境条件、水动力条件、人类活动及气象条件4个方面阐述了三峡水库支流CH_(4)排放的影响因素。1)水环境条件:支流水华后藻类衰亡分解过程会驱动CH_(4)释放,且藻类的演替过程会加剧CH_(4)的产生;温度可以直接影响CH_(4)的生成速率和消耗速率,也能通过促进藻的生长间接影响CH_(4)排放;支流相对较低的甲烷氧化菌丰度是其CH_(4)通量较高的原因之一。2)水动力条件:蓄水期CH_(4)主要以扩散的方式进行释放,支流较低的流速促进了悬浮物的沉积,上游沉积物中的CH_(4)含量高于下游;泄水期CH_(4)主要以冒泡的方式进行释放,下游沉积物中TOC急剧增加,但干流的入侵会削弱支流的温度分层,破坏藻类生长环境,间接影响CH_(4)通量。3)人类活动:农业耕作使支流水体中的营养物浓度增加,甲烷氧化菌的丰富度降低,细菌群落的营养相关代谢增强;建设用地扩大、支流筑坝增加抑制了有机物的传输,增加了水体中的产CH_(4)底物,促进了CH_(4)的产生。4)气象条件:降雨会携带更多营养物质进入支流,同时会增加水体浊度、破坏水体的温度分层,从而对CH_(4)的产生和传输过程造成影响。最后对未来的研究热点进行了展望,以期为三峡水库CH_(4)排放的控制和管理提供参考。

输水明渠着生藻类群落结构特征对水动力条件的响应

明渠输水系统的着生藻类异常增殖会淤塞拦污栅,降低明渠输水能力,并增加清理工作压力。目前,有关着生藻类对水动力的响应研究多在天然河流、湖泊中开展野外原型观测,针对混凝土衬砌表面着生藻类的水动力研究仍然少见。由于混凝土基质与泥沙基质的显著差异,着生藻类在衬砌明渠和自然水体中对水动力的响应特性不同。为探究水动力对明渠着生藻类生长及群落结构的影响,特开展明渠中着生藻类的培养观测及水动力冲刷实验。通过分析着生藻类叶绿素a含量、群落结构、无灰干重、细胞密度等指标,以探究不同基质粗糙度、不同生长阶段的着生藻类对不同水动力条件的响应。结果表明:着生藻类建群过程具有3个明显阶段,分别为迟滞期、指数生长期、稳定期;随着流速增大,着生藻类生物量先上升后下降,当流速v>0.6 m/s时,着生藻类的生长被显著抑制;冲刷流速增大至v=0.8 m/s的2天后,着生藻类生物量显著减少,群落多样性下降。在着生藻类建群迟滞期(实验中约3周),该阶段提高流速对着生藻类生物量的冲刷剥离效果最明显;基质粗糙度越小,着生藻类建群迟滞期越长,通过水力冲刷的除藻效果越明显。本研究探索了不同水动力条件下明渠着生藻类的响应规律,有助于认识明渠着生藻类的群落特征,可为明渠输水系统内着生藻类水力调控提供重要依据。

涟水高沟地区承压地下水可更新性研究

为合理开发利用和保护地下水资源,评价区域地下水可更新性成为当前首要解决的问题。本文从定性和定量两个角度进行分析研究,首先从区域水文地质条件与地下水水动力等方面,进行地下水系统划分及特征研究,分析含水层空间结构及补径排条件;其次在收集利用以往测试资料基础上,通过现场采样分析,开展不同水体环境同位素特征研究;最后利用水均衡法计算地下水可更新能力指标。研究结果表明:涟水高沟地区承压水具备地下水补给通道,主要接受上游山区侧向径流补给,且在开发利用过程中不会引发地面沉降等环境地质问题;地下水水龄2万年左右,水循环更新周期上千年,可认为其具有一定的更新能力,不属于难以更新的地下水;同时,地下水的合理开发利用有助于加快地下水循环速率,进一步提高地下水更新能力。