CFD-based numerical analysis of a variable cross-section cylinder

Using ANSYS-CFX, a general purpose fluid dynamics program, the vortex-induced vibration (VIV) of a variable cross-section cylinder is simulated under uniform current with high Reynolds numbers. Large eddy simulation (LES) is conducted for studying the fluid-structure interaction. The vortex shedding in the wake, the motion trajectories of a cylinder, the variation of drag and lift forces on the cylinder are analyzed. The results show that the vortices of variable cross-section cylinder are chaotic and are varying along the cylinder. In places where cross-sections are changing significantly, the vortices are more irregular. The motion trail of the cylinder is almost the same but irregular. The drag and lift coefficients of the cylinder are varying with the changes of diameters.     

探空观测黑名单检查在变分同化系统中的应用

针对探空观测资料使用造成的某些区域GRAPES分析场存在虚假的高、低压系统问题,该文通过对比全球探空资料的位势高度观测与NCEP分析场,统计站点中观测质量较差的时次出现频数,确定探空位势高度观测黑名单。研究表明:500 hPa在印度地区、北大西洋和南极洲附近的探空位势高度观测与NCEP分析场的均方根误差在30 gpm以上的站点较多,且位势高度观测不可靠观测比率为20%以上的站点主要集中这些区域,以上观测站均列入黑名单。文中在GRAPES全球三维变分分析场的质量控制中加入探空位势高度观测黑名单检查,通过6 h分析预报循环试验表明:探空位势高度观测黑名单检查能有效提高分析场质量,GRAPES位势高度分析场在南极洲附近和印度地区有所改善。     

Ocean Model Open Boundary Conditions with Volume,Heat and Salinity Conservation Constraints简

Open boundary conditions （OBCs） for a regional ocean model that can be integrated stably over a long timeframe, as well as satisfy the volume, heat and salinity conservation constraints, were developed. First, the idea that the inward and outward flux information can be treated separately in the OBCs was adopted. Second, in order to maintain the property that the volume, heat and salinity remains conserved in the simulation domain, conservation constraints were added to the OBCs, and an inverse method utilized to solve the constraint equations. Ideal experiments were designed to investigate the conservation property, and the OBCs were found to work efficiently to maintain the volume, heat and salinity conservation. It was found that simulations were comparable to observations when the OBCs were applied to a regional ocean model.     

甘肃清水县地质灾害类型、形成条件及发育规律分析

清水县是甘肃省地质灾害较为严重的地区之一。本文根据清水县地质灾害调查与区划项目野外调查成果资料,在概述县域自然地理条件及地质背景的基础上,全面阐述了全县已有的地质灾害类型及特征,从地形地貌、岩土体类型与结构、地质构造、大气降水、人类工程活动5个方面深入分析了地质灾害的形成条件,并探讨了地质灾害的分布发育规律,以期为区域地质灾害防治提供科学依据。     

庐江-枞阳火山岩矿集区南部城山地区地质条件和成矿规律研究

庐江-枞阳(庐枞)火山岩矿集区南部作为寻找沉积-叠加改造型铁铜矿的有利地区一直没有较大找矿突破,该区近几年勘查取得了一定地质找矿进展。本文主要在野外地质调查的基础上,对庐江-枞阳火山岩矿集区南部城山地区地质条件进行总结分析,重新认识了区内地层的含矿性以及构造特征,发现了大量矿化线索。在研究区内发现了4条与岩浆热液有关的铜铁铅锌矿化带,而且具有一定规律,空间上平面均为北东东、东西向,垂向上从深到浅具有从钼到铜铅锌矿化分带。成矿时间从126.5Ma开始。研究区内大规模磁铁矿化以及铜铅锌矿化的存在,表明深部具有较好找矿潜力。     

四川中坝气田雷口坡组成藏条件及油气主控因素

通过对四川盆地西北部中坝气田中三叠统雷口坡组气藏已发现油气与有利沉积相带、局部构造、等关系的分析,结合试采试油资料与储层厚度、物性与录井显示关系的统计分析,总结认为油气成藏发育了多套烃源岩,具有良好的储集条件和保存条件。通过对各个构造运动阶段雷口坡气藏被改造与再形成的分析,提出油气主控因素是后期构造运动的影响,主要经历了印支期、燕山期和喜山期构造运动的改造形成的古圈闭,油气藏受到破坏然后再形成的整个过程。该主识对中坝气田未来的勘探开发具有指导意义。     

某深埋特长隧洞线路比选方案研究

滇中引水工程香炉山隧洞为特长深埋隧洞,起点位于冲江河右岸石鼓镇,终点位于洱海边的长育村,此前已对该段进行东、中、西等多方向的较大范围线路比选[1]。通过已有地质资料进行线路对比,提出了8条比选线路,从各线路长度和形态,存在的主要工程地质问题,隧洞地质、施工条件等进行比较、分析、研究,最终选定中4线为推荐方案。论文简要介绍了隧洞线路选线方案、比选的思路和方法,以期为相关工程的规划设计提供参考。     

江苏平原地区(淮河流域)潜水碘含量控制因素探讨

本文通过工作区潜水碘含量的分布特点,与所处土壤、水文地质条件、地形地貌等一起进行综合分析,对地下水中碘的控制因素有了一个全新的认识:与前人认为地下水中碘的含量与有机质成正比的观点不同的是,本文认为地下水中碘的含量与有机质含量无固定关系,但有机质有助于促进水溶性碘的增加,相似水文地质条件下成正比;地下水径流条件对潜水碘含量影响重大,径流条件较好的丘陵、岗地往往较低,地势低平、径流条件较差的洼地和泛滥沉积区往往为高碘地区;相同水文地质条件下,地下水中的碘含量与土壤中的含量成正比;碘的另一重要特征是在地下水中的浓度较为稳定,随时间、开采而变化不大。     

四川省蓬溪县安置点地质灾害危险性评估

通过对天福镇三关村安置点建设用地的地形地貌、地层岩性、地质构造与区域稳定性、水文地质条件等工程地质条件的分析,对场地进行了危险性现状评估、预测评估及综合评估,并提出了灾害防治建议。     

Jump conditions and dynamic surface tension at permeable interfaces such as the inner core boundary

We consider a fluid crossing a zone of rapid density change, so thin that it can be considered as a density jump interface. In this case, the normal velocity undergoes a jump. For a Newtonian viscous fluid with low Reynolds number (creeping flow) that keeps its rheological properties within the interface, we show that this implies that the traction cannot be continuous across the density jump because the tangential stress is singular. The appropriate jump conditions are established by using the calculus of distributions, taking into account the curvature of the interface as well as the density and viscosity changes. Independently of any intrinsic surface tension, a dynamic surface tension appears and turns out to be proportional to the mass transfer across the interface and to a coefficient related to the variations of density and viscosity within the interface. Explicit solutions are exhibited to illustrate the importance of these new jump conditions. The example of the Earth's inner core crystallisation is questioned.