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computational properties of a new horizontal staggered grid

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Science china Earth Sciences 2005年第9期48卷 1559-1568页

作者： LIU YudiState Key laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, beijing 100029, china Institute of Meteorology, PLA university of Science and Technology, Nanjing 211101, china State Key laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics Institute of Atmospheric Ph Chinese Academy of Sciences Beijing China Institute of Meteorology PLA University of Science and Technology Nanjing China

This paper presents a new horizontal staggered grid (LE grid), which defines h at a gridpoint, and both u and v at the same mid-gridpoint along the x and y directions. A general method is used to deduce the dispersion relationships of describing inertia gravity waves on LE grid and Arakawa A―E grids, which are then compared with the analytical solution (AS) in re- solved or under-resolved cases, using two-order central difference or four-order compact differ- ence scheme from the frequency and group velocity. Results show that in both resolved and under-resolved cases, no matter whether two-order central difference or four-order compact dif- ference scheme is used, the frequency and group velocity discrete errors on LE grid in describing inertia gravity waves are smaller than those of Arakawa A―E grids. At the same time, it is only on LE or Arakawa grid C that the employment of a compact difference scheme of higher difference precision can improve their accuracy in describing inertia gravity waves. However, as for the other four grids (Arakawa A,B,D and E), when the difference precision increases, the accuracy of simulating inertia gravity waves decreases.

关键词： horizontal staggered grid, inertia gravity wave, LE grid, Arakawa A-E grid, compact difference scheme, central difference.

Design of a new dynamical core for global atmospheric models based on some efficient numerical methods

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Science china Mathematics 2004年第Z1期47卷 4-21页

作者： WANG Bin, WAN Hui, Jl Zhongzhen, ZHANG Xin, YU Rucong, YU Yongqiang & LIU HongtaoState Key laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, beijing 100029, china Department of computational Mathematics, Academy of Mathematics and System Sciences, Peking university, beijing 100871, china State Key laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Department of computational Mathematics Academy of Mathematics and System Sciences Peking University Beijing China

A careful study on the integral properties of the primitive hydrostatic balance equations for baroclinic atmosphere is carried out, and a new scheme todesign the global adiabatic model of atmospheric dynamics ispresented. This scheme includes a method of weighted equal-areamesh and a fully discrete finite difference method with quadraticand linear conservations for solving the primitive equationsystem. Using this scheme, we established a new dynamical corewith adjustable high resolution acceptable to the availablecomputer capability, which can be very stable without anyfiltering and smoothing. Especially, some important integralproperties are kept unchanged, such as the anti-symmetries of thehorizontal advection operators and the vertical convectionoperator, the mass conservation, the effective energy conservationunder the standard stratification approximation, and so on. Somenumerical tests on the new dynamical core, respectively regardingits global conservations and its integrated performances inclimatic modeling, incorporated with the physical packagesfrom the Community Atmospheric Model Version 2 (CAM2) of nationalCenter for Atmospheric Research (NCAR), are included.

关键词： dynamical core, equal-area mesh, anti-symmetry, effective energy conservation.

Unsteady aerodynamic modeling based on POD-observer method

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Science china(Technological Sciences) 2010年第8期53卷 2032-2037页

作者： YANG Chao,LIU XiaoYan &WU ZhiGang beijing university of Aeronautics and Astronautics,beijing 100191,china beijing university of Aeronautics and Astronautics Beijing China

A new hybrid approach to constructing reduced-order models(ROM)of unsteady aerodynamics applicable to aeroelastic analysis is presented by using proper orthogonal decomposition(POD)in combination with observer *** modes are generated through POD by sampling observations of solutions derived from the full-order *** response in the POD training is projected onto the fluid modes to determine the time history of the modal *** resulting data are used to extract the Markov parameters of the low-dimensional model for modal amplitudes using a related deadbeat *** state-space realization is synthesized from the system's Markov parameters that are processed with the eigensystem realization *** POD-observer method is applied to a two-dimensional airfoil system in subsonic flow *** results predicted by the ROM are in general agreement with those from the full-order *** ROM obtained by the hybrid approach captures the essence of a fluid system and produces vast reduction in both degrees of freedom and computational time relative to the full-order model.

关键词： aeroelasticity aerodynamic modeling proper orthogonal decomposition observer eigensystem realization algorithm

Numerical Simulation of Muti-Jet Ejector

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Numerical Simulation of Muti-Jet Ejector

Evolution of desertification in a two-dimensional energy balance model coupled with thermodynamics and dynamics

2012 national Conference on Information Technology and Computer Science

作者： Lin JIANG 1 School of Aeronautic Science and Engineering,beihang university,beijing 100191,P.R.china Song-ping WU 1,2,3 2.national laboratory for computational fluid dynamics,beihang university,beijing 100191,P.R.china 3.Ministry of Education Key laboratory of fluid Mechanics,beihang university,beijing 100191,P.R.china

The influence of nozzle location on the efficiency of ejector was discussed according to lots of calculated *** nozzle location will have influence on the efficiency of ejector without modifying ejector structure.

关键词： ejector efficiency nozzle location collision loss

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Science china Earth Sciences 2010年第11期53卷 1726-1733页

作者： CHAO JiPing1,2 & LI YaoKun3,4 1national Marine Environmental Forecasting Center, beijing 100081, china 2First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, china 3State Key laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, beijing 100029, china 4Graduate university of Chinese Academy of Sciences, beijing 100049, china national Marine Environmental Forecasting Center Beijing China First Institute of Oceanography State Oceanic Administration Qingdao China State Key laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Graduate university of Chinese Academy of Sciences Beijing China

The relationship between desert evolution and change in albedo has been investigated quasi-analytically using a zonal mean two-dimensional energy balance model which considers the radiation transmission process due to thermodynamics and bound- ary layer movement caused by kinetics. A climate state including temperature, zonal wind, meridional wind and vertical wind can be simulated according to the current zonal distribution of albedo. Given desert distribution, characterized by the value and distribution of albedo, the response of climate on albedo has been studied to analyze the evolution of desert climate. One significant result is that the simple model can reproduce mean meridional circulation. Another result indicates that climate corresponds to two equilibria. This happens when the junction temperature between vegetation and desert is higher than a certain critical value. As for the first equilibrium, the desert belt is predicted to move southward in the northern hemisphere with the increasing values of albedo, which corresponds to the current trend of climate change. For the second equilibrium, vegetation will expand northward with increasing values of albedo, which would indicate a narrowing of the desert belt. In order to determine if the two equilibria exist, new physical models are needed.

关键词： two-dimensional energy balance model desertification two equilibria

MB_8^(2-) (M=Be,Mg,Ca,Sr,and Ba):Planar octacoordinate alkaline earth metal atoms enclosed by boron rings

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Science china Chemistry 2010年第8期53卷 1737-1745,1829-1832页

作者： PU ZhiFeng1,GE MaoFa1 & LI QianShu2 1State Key laboratory for Structural Chemistry of Unstable and Stable Species beijing national laboratory for Molecular Sciences (BNLMS) Institute of Chemistry,Chinese Academy of Sciences,beijing 100190,china 2Center for computational Quantum Chemistry,South china Normal university,Guangzhou 510631,china State Key laboratory for Structural Chemistry of Unstable and Stable Species beijing national laboratory for Molecular Sciences (BNLMS) Institute of Chemistry Chinese Academy of Sciences Beijing China Center for computational Quantum Chemistry South China Normal University Guangzhou China

Complexes involving planar octacoordinate alkaline earth metal atoms in the centers of eight-membered boron rings have been investigated by two density functional theory (DFT) ***82-with D8h symmetry is predicted to be stable,both geometrically and electronically,since a good match is achieved between the size of the central beryllium atom and the eight-membered boron *** contrast,the other alkaline earth metal atoms cannot be stabilized in the center of a planar eight-membered boron ring because of their large *** following the out-of-plane imaginary vibrational frequency,pyramidal C8v MgB82-,CaB82-,SrB82-,and BaB82-structures are *** presence of delocalized π and σ valence molecular orbitals in D8h BeB82-gives rise to aromaticity,which is reflected by the value of the nucleus-independent chemical *** D8h BeB82-structure is confirmed to be the global minimum on the potential energy surface.

关键词： density functional theory octacoordinate alkaline earth metal aromatic molecular orbital

Numerical Simulation Study of Aerodynamic Characteristic on Hypersonic Aircraft

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Numerical Simulation Study of Aerodynamic Characteristic on ...

Nonlinear local Lyapunov exponent and atmospheric predictability research

2012 national Conference on Information Technology and Computer Science

作者： Jiang CHEN School of Aeronautic Science and Engineering,beihang university,beijing 100191,P.R.china Song-ping WU School of Aeronautic Science and Engineering,beihang university,beijing 100191,P.R.china national laboratory for computational fluid dynamics,beihang university,beijing 100191,P.R.china Ministry of Education Key laboratory of fluid Mechanics,beihang university,beijing 100191,P.R.china

In this paper,a three dimension model that is similar to the hypersonic cruise aircraft X-51A has been generated by using a graphics processing technology and an anti-modeling method from the published pictures and related articles about the *** paper adopts the Harten-Yee’s scheme to simulate the aircraft at the cruise state of M ∞ =6,α=6°.And related results are *** the basic characteristics of the flow-field qualitatively and find that the result is kept well with the designed *** it means that the model could be used for the further related research.

关键词： hypersonic aerodynamic characteristic numerical simulation

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Science china Earth Sciences 2006年第10期49卷 1111-1120页

作者： CHEN Baohua1, LI Jianping1,2 & DING Ruiqiang2 1. College of Atmospheric Sciences, Lanzhou university, Lanzhou 730000, china 2. State Key laboratory of Numerical Modeling for Atmospheric Science and Geophysical fluid dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, beijing 100029, china College of Atmospheric Sciences Lanzhou University Lanzhou China State Key laboratory of Numerical Modeling for Atmospheric Science and Geophysical fluid dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

Because atmosphere itself is a nonlinear system and there exist some problems using the linearized equations to study the initial error growth, in this paper we try to use the error nonlinear growth theory to discuss its evolution, based on which we first put forward a new concept: nonlinear local Lyapunov exponent. It is quite different from the classic Lyapunov exponent because it may characterize the finite time error local average growth and its value depends on the initial condition, initial error, variables, evolution time, temporal and spatial scales. Based on its definition and the at-mospheric features, we provide a reasonable algorithm to the exponent for the experimental data, obtain the atmospheric initial error growth in finite time and gain the maximal prediction time. Lastly, taking 500 hPa height field as example, we discuss the application of the nonlinear local Lyapunov exponent in the study of atmospheric predictability and get some reliable results: atmospheric predictability has a distinct spatial structure. Overall, predictability shows a zonal distribution. Prediction time achieves the maximum over tropics, the second near the regions of Antarctic, it is also longer next to the Arctic and in subtropics and the mid-latitude the predictability is lowest. Particularly speaking, the average prediction time near the equation is 12 days and the maximum is located in the tropical Indian, Indonesia and the neighborhood, tropical eastern Pacific Ocean, on these regions the prediction time is about two weeks. Antarctic has a higher predictability than the neighboring latitudes and the prediction time is about 9 days. This feature is more obvious on Southern Hemispheric summer. In Arctic, the predictability is also higher than the one over mid-high latitudes but it is not pronounced as in Antarctic. Mid-high latitude of both Hemispheres (30°S―60°S, 30°―60°N) have the lowest predictability and the mean prediction time is just 3―4 d. In addition, predictab

关键词： nonlinear, local, Lyapunov exponent, atmospheric predictability, maximal prediction time.

THE UNCONDITIONAL STABLE DIFFERENCE METHODS WITH INTRINSIC PARALLELISM FOR TWO DIMENSIONAL SEMILINEAR PARABOLIC SYSTEMS

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Journal of computational Mathematics 2003年第1期21卷 63-70页

作者： Guangwei Yuanf Longjun Shen(national laboratory of computational Physics, Institute of Applied Physics and computational Mathematics, P.O. Box 8009, beijing, 100088, china) Ningbo university Institute of Applied Physics and computational Mathematics P.O. Box 8009 National Laboratory of Computational Physics 北京 100088

In this paper we are going to discuss the difference schemes with intrinsic parallelism for the boundary value problem of the two dimensional semilinear parabolic systems. The unconditional stability of the general finite difference schemes with intrinsic parallelism is justified in the sense of the continuous dependence of the discrete vector solution of the difference schemes on the discrete data of the original problems in the discrete w2(2,1)norms. Then the uniqueness of the discrete vector solution of this difference scheme follows as the consequence of the stability.

关键词： Difference Scheme Intrinsic Parallelism Two Dimensional Semilinear Parabolic System Stability.