依据本科评估加强石油高校流体力学实验室建设的探索与实践

流体力学实验是面向全校的专业基础实验,中国石油大学(北京)流体力学实验室承担着全校9个本科专业的实验教学任务,是本科教学的一个重要环节,也是本科评估的重要组成部分。针对新时期高等教育质量保障与本科评估的要求,流体力学实验室结合石油高校特点,从实验教学体系建设,实验教学、实验室开放、设备配置及安全实验环境构建等多个方面进行实践探索,以保障石油人才的培养质量,帮助学生达成学习目标。

石油高校流体力学实验室安全管理实践及探索

针对石油高校流体力学实验室特点,结合实验室安全管理的实践经验,分析高校流体力学实验室通常存在的安全问题,可能发生的安全事故以及必要的应对措施,探索加强实验室安全管理的方式方法。

CFD技术不再是“阳春白雪”——访国家计算流体力学实验室主任北京航空航天大学李椿萱院士

CFD(计算流体动力学)技术是一种计算机模拟技术,集流体力学、数值计算方法以及计算机图形学于一体。CFD技术的发展源于核武器、航空航天等一些高科技领域。过去由于CFD技术涉及复杂的流体力学理论让人望而却步。如今,随着计算机以及相关技术的迅速发展,特别是一些CFD商业软件的出现,CFD技术已不再是停留在“象牙塔”中的高深学问,它已在各个工业领域中发挥出越来越大的作用。CFD技术在我国家电行业内的应用尚还处于起步阶段,其相关的一些情况还不为广大家电行业的工程师们所了解。为此本刊记者专门走访了国家计算流体力学重点实验室主任北京航空航天大学李椿萱院士,请他聊一聊有关CFD应用中的一些问题。

席葆树的科研精神万年青

明朝刘宗周曾著过一册《人谱》,书中列举古来许多贤人的嘉言懿行,其中有一节记道“为文者,当先器识而后文艺。”译为现代话,即“首重人格修养,次则文艺学习。”此圣理推及到席葆树教授身上是再贴切不过了。 席葆树教授,清华大学生物力学实验室主任,博士生导师,同时兼任希必实公司的总经理。席教授长期从事实验流体力学和生物流体力学的研究,并做出了重要的贡献。1979年,他被越级提升为副教授,1985年提升为教授。1987年荣获国家级有突出贡献的中青年专家称号。

蓝天情怀 赤子丹心——记中国工程院院士、北京航空航天大学李椿萱教授

北航飞行器设计及应用力学系教授、中国工程院李椿萱院士,1972年美国纽约州立大学博士毕业;1980年回国,曾先后任北航五系教授、博士生导师,北航流体力学所所长,国家“863”计划大型运载火箭及天地往返运输系统主题专家组气动力/热责任专家, “863”计划航天技术领域气动力/热专题组组长,国家计算流体力学实验室主任等职。因其卓有成效的工作,先后获得了全国优秀教师、国防科工委“863”计划先进工作者、全国中青年有突出贡献专家等荣誉称号。

Simulation of the East Asian Subtropical Westerly Jet Stream with GFDL AGCM (AM2.1)

The present study validated the capability of the AM2.1,a model developed at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL),in reproducing the fundamental features of the East Asian Subtropical Westerly Jet Stream (EASWJ).The main behaviors of the EASWJ are also investigated through the reanalysis of observational NCEP/NCAR data.The mean state of the EASWJ,including its intensity,location,structure,and seasonal evolution is generally well-portrayed in the model.Compared with the observation,the model tends to reproduce a weaker jet center.And,during summer,the simulated jet center is northward-situated.Results also demonstrate the model captures the variability of EASWJ during summer well.The results of the empirical orthogonal function (EOF) applied on the zonal wind at 200 hPa (U200) over East Asia for both the observation and simulation indicate an inter-decadal shift around the late 1970s.The correlation coefficient between the corresponding principle components is as great as 0.42 with significance at the 99% confidence level.

The Spatial Patterns of Initial Errors Related to the “Winter Predictability Barrier” of the Indian Ocean Dipole

In this study, using the Geophysical Fluid Dynamics Laboratory Climate Model version 2pl （GFDL CM2pl） coupled model, the winter predictability barrier （WPB） is found to exist in the model not only in the growing phase but also the Indian Ocean dipole （IOD） decaying phase of positive events due to the effect of initial errors. In particular, the WPB is stronger in the growing phase than in the decaying phase. These results indicate that initial errors can cause the WPB. The domi- nant patterns of the initial errors that cause the occurrence of the WPB often present an eastern-western dipole both in the surface and subsurface temperature components. These initial errors tend to concentrate in a few areas, and these areas may represent the sensitive areas of the predictions of positive IOD events. By increasing observations over these areas and eliminating initial errors here, the WPB phenomenon may be largely weakened and the forecast skill greatly improved.

Impact of European Black Carbon on East Asian Summer Climate

The remote response of the East Asian summer monsoon （EASM） to European black carbon （EUBC） aerosols was studied by using an ensemble of sensitivity experiments with the Geophysical Fluid Dynamics Laboratory （GFDL） atmospheric general circulation model （AGCM） Atmospheric Model version 2.1 （AM2.1）.The results show that EUBC causes an enhanced EASM.The resulted enhanced southwesterly brings more moisture supply from the Bay of Bengal,which causes an increase in precipitation over the Yangtze River valley,northeastem China,the eastern part of the Yellow River valley,and the Tibetan Plateau.Diagnostic examination suggests that EUBC induces enhanced tropospheric heating over most of the Eurasian Continent through a propagating wave train and horizontal air temperature advection.This phenomenon results in intensified thermal contrast between land and ocean,which accounts for the enhanced EASM.Moreover,reductions in EUBC emission in 1992 may have contributed to decadal weakening of the EASM in the early 1990s.

Tropical Pacific Decadal Variability in Subsurface Temperature

The nature decadal variability of the equatorial Pacific subsurface temperature is examined in the control simulation with the Geophysical Fluid Dynamics Laboratory coupled model CM2.1.The dominant mode of the subsurface temperature variations in the equator Pacific features a 20-40 year period and is North-South asymmetric about the equator.Decadal variations of the thermocline are most pronounced in the southwest of the Tropical Pacific.Decadal variation of the north-south asymmetric Sea Surface wind in the tropical Pacific,especially in the South Pacific Convergence,is the dominant mechanism of the nature decadal variation of the subsurface temperature in the equatorial Pacific.

CFD based extraction column design-Chances and challenges

This paper shows that one-dimensional （I-D） [and three-dimensional （3-D） computational fluid dynamics （CFD）] simulations can replace the state-of-the-art usage of pseudo-homogeneous dispersion or back mixing models. This is based on standardized lab-scale cell experiments for the determination of droplet rise, breakage, coalescence and mass transfer parameters in addition to a limited number of additional mini-plant experiments with original fluids. Alternatively, the hydrodynamic parameters can also be derived using more sophisticated 3- D CFD simulations. Computational 1-D modeling served as a basis to replace pilot-plant experiments in any column geometry. The combination of 3-D CFD simulations with droplet population balance models （DPBM） increased the accuracy of the hydrodynamic simulations and gave information about the local droplet size. The high computational costs can be reduced by open source CFD codes when using a flexible mesh generation. First combined simulations using a three way coupled CFD/DPBM/mass-transfer solver pave the way for a safer design of industrial-sized columns, where no correlations are available.

Effect of floor level slit exhaust ventilation system on distribution of house dust

Based on the fact that the house dust usually falls on the ground, the floor level slit exhaust ventilation system including inlet located at the ceiling and outlet of slit exhaust installed at comer between wall and floor was considered. Experiments and simulations were performed to investigate the flow and diffusion fields that are affected by this floor level slit exhaust ventilation system. The characteristics of airflow with experiments and computation fluid dynamics （CFD） are generally similar except airflow at the location of impinging flow and the location right below the inlet. Riboflavin particles were used as the house dust. For the spatial distribution of riboflavin particles in the ventilation system before operation, due to the influence of gravity, different sizes of particles show smooth decay curve. After floor level slit exhaust ventilation system is operated, the decay rate of the particles becomes faster than that after the ventilation system is powered on, and the particles with diameter of 0.5-3.0 μm in the experimental data and calculated values show good agreement.

Arctic Oscillation Responses to Black Carbon Aerosols Emitted from Major Regions

The responses of the Arctic Oscillation(AO) to global black carbon(BC) and BC emitted from major regions were compared using the atmospheric general circulation model Geophysical Fluid Dynamics Laboratory(GFDL) atmospheric general circulation model(AGCM) Atmospheric Model version 2.1(AM2.1). The results indicated that global BC could induce positive-phase AO responses, characterized by negative responses over the polar cap on 500 h Pa height fields, and zonal mean sea level pressure(SLP) decreasing while zonal wind increasing at 60°, with the opposite responses over midlatitudes. The AO indices distribution also shifted towards positive values. East Asian BC had similar impacts to that of global BC, while the responses to European BC were of opposite sign. South Asian BC and North American BC did not affect the AO significantly. Based on a simple linear assumption, we roughly estimated that the global BC emission increase could explain approximately 5% of the observed positive AO trend of +0.32 per decade during 1960 to 2000.

A finite volume algorithm based on overlapping meshes for simulation of hydrodynamic problems

A finite volume algorithm was established in order to investigate two-dimensional hydrodynamic problems. These include viscous free surface flow interaction with free rigid bodies in the case of large and/or relative motions. Two-phase flow with complex deformations at the interface was simulated using a fractional step-volume of fluid algorithm. In addition, body motions were captured by an overlapping mesh system. Here, flow variables are transferred using a simple fully implicit non-conservative interpolation scheme which maintains the second-order accuracy of implemented spatial discretisation. Code was developed and an appropriate set of problems investigated. Results show good potential for development of a virtual hydrodynamics laboratory.

大鹏同风起——记北京大学王健平教授

对王健平来说，１９９６年１２月２０日，是他人生中一个重要的日子。这一天，在日本留学、工作长达１５年的王健平回到了祖国，被北京大学力学与工程科学系聘为教授，并进入北大湍流国家重点实验室工作。王健平人生的书卷翻开了全新的一页。这一天，正好是王健平３５岁的...