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Wave-mean flow interaction and its relationship with the atmospheric energy cycle with diabatic heating

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Science China Earth Sciences 2005年第8期48卷 1293-1302页

作者： DUAN Anmin WU Guoxiong State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

Based on the traditional theory of wave mean flow interaction, an improved quasi-geostrophic Eliassen-Palm flux with diabatic heating included is deduced. It is shown that there exists an intrinsic relation between the atmospheric energy cycle derived by Lorenz and the wave energy transfer derived by Eliassen and Palm. From this relation it becomes clear that the energy propagation process of large-scale stationary wave is indeed a part of Lorenz energy cycle, and the energy transform from mean flow to wave equals the global mass integral of the divergence of local wave energy flux or the global integral of local wave energy. The diagnostic results by using NCEP/NCAR reanalysis data suggest that the classical adiabatic Eliassen-Palm flux relation can present only the wintertime wave energy transformation. For other seasons, however, the diabatic effect must be taken into account.

关键词： wave-mean flow interaction, Eliassen-Palm flux, diabatic heating, Lorenz energy cycle, wave energy.

Study on the unified algorithm for three-dimensional complex problems covering various flow regimes using Boltzmann model equation

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Science China(Physics,Mechanics & Astronomy) 2009年第1期52卷 124-138页

作者： LI ZhiHui1,2 & ZHANG HanXin1 1 National Laboratory for Computational fluid dynamics, Beijing 100083, China 2 China Aerodynamics Research and Development Center, Hypervelocity Aerodynamics institute, Mianyang 621000, China National Laboratory for Computational fluid dynamics Beijing China China Aerodynamics Research and Development Center Hypervelocity Aerodynamics Institute Mianyang China

The Boltzmann simplified velocity distribution function equation describing the gas transfer phenomena from various flow regimes will be explored and solved numerically in this study. The discrete velocity ordinate method of the gas kinetic theory is studied and applied to simulate the complex multi-scale flows. Based on the uncoupling technique on molecular movement and colliding in the DSMC method, the gas-kinetic finite difference scheme is constructed to directly solve the discrete velocity distribution functions by extending and applying the unsteady time-splitting method from computational fluid dynamics. The Gauss-type discrete velocity numerical quadrature technique for different Mach number flows is developed to evaluate the macroscopic flow parameters in the physical space. As a result, the gas-kinetic numerical algorithm is established to study the three-dimensional complex flows from rarefied transition to continuum regimes. The parallel strategy adapted to the gas-kinetic numerical algorithm is investigated by analyzing the inner parallel degree of the algorithm, and then the HPF parallel processing program is developed. To test the reliability of the present gas-kinetic numerical method, the three-dimensional complex flows around sphere and spacecraft shape with various Knudsen numbers are simulated by HPF parallel computing. The computational results are found in high resolution of the flow fields and good agreement with the theoretical and experimental data. The computing practice has confirmed that the present gas-kinetic algorithm probably provides a promising approach to resolve the hypersonic aerothermodynamic problems with the complete spectrum of flow regimes from the gas-kinetic point of view of solving the Boltzmann model equation.

关键词： Boltzmann model equation kinetic theory velocity distribution function discrete velocity ordinate technique hypersonic flow parallel computing numerical methods

Warming in the Northwestern Indian Ocean Associated with the El Nio Event

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Advances in Atmospheric Sciences 2008年第2期25卷 246-252页

作者：袁媛周文杨辉李崇银 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Department of Physics and Materials Science. City University of Hong Kong State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences

This paper investigates possible warming effects of an E1 Nifio event on the sea surface temperature anomaly （SSTA） in the northwestern Indian Ocean. Most pure positive Indian Ocean dipole （IOD） events （without an E1 Nifio event co-occurring） have a maximum positive SSTA mainly in the central Indian Ocean south of the equator, while most co-occurrences with an E1 Nifio event exhibit a northwest-southeast typical dipole mode. It is therefore inferred that warming in the northwestern Indian Ocean is closely related to the E1 Nifio event. Based on the atmospheric bridge theory, warming in the northwestern Indian Ocean during co-occurring cases may be primarily caused by relatively less latent heat loss from the ocean due to reduced wind speed. The deepened thermocline also contributes to the warming along the east coast of Africa through the suppressed upwelling of the cold water. Therefore, the E1 Nifio event is suggested to have a modulating effect on the structure of the dipole mode in the tropical Indian Ocean.

关键词： positive Indian Ocean dipole E1 Nifio latent heat flux thermocline

Localization of rare earth ions in an inhomogeneous magnetic field toward their magnetic separation

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Journal of Rare Earths 2022年第10期40卷 1598-1605页

作者： Barbara Fritzsche Zhe Lei Xuegeng Yang Kerstin Eckert TU Dresden Institute of Process Engineering and Environmental Technology01062DresdenGermany Helmholtz-Zentrum Dresden-Rossendorf(HZDR) Institute of Fluid DynamicsBautzner Landstrasse 40001328DresdenGermany

Efficient extraction and recycling methods are an important issue for rare earth elements(REE). The significant differences in their magnetic moments make magnetic separation a promising step. Although the magnetic field gradient manipulation of ions seemed to be impossible, the robust enrichment of some paramagnetic RE ions was found in the vicinity of the magnet. The studies in recent years resolved the physical paradox of why, despite the Brownian motion of the ions, there is a reproducible enrichment of RE ions in magnetic field gradients. The existence of trigger process and energy barrier was ***, these studies usually used only high paramagnetic ions, e.g., Dy(Ⅲ) or Ho(Ⅲ). This work verifies the theory of the possible magnetic separation for 8 different rare earth ions, respectively. For this purpose, concentration distribution in rare earth chloride solutions were measured using a MachZehnder interferometer. The magnetic field was assured by a Halbach configuration to enhance the effect. The results show the classification of RE solutions into 2 classes: Class I contains the REs with low magnetic moment, whereas Class II includes the REs of high magnetic moment. Only the latter group shows the enrichment of ions in the vicinity of the magnet which encourages the implementation of magnetic separation into existing hydrometallurgical technology to enhance the selectivity of REE.

关键词： Magnetic separation Paramagnetic rare earth ions Enrichment Halbach array Interferometry Aqueous solution

Heating status of the Tibetan Plateau from April to June and rainfall and atmospheric circulation anomaly over East Asia in midsummer

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Science China Earth Sciences 2005年第2期48卷 250-257页

作者： DUAN Anmin LIU Yimin WU Guoxiong State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China

Based on the 1958-1999 monthly averaged reanalysis data of the National Center for Environmental Prediction(NCEP)/National Center for Atmospheric Research(NCAR)and the rainfall data of 160 Chinese surface stations,the relationship between rainfall and the atmospheric circulation anomaly over East Asia(EA)in July and the sensible heating(SH)over the Tibetan Plateau(TP)from April to June(AMJ)is investigated by using the rotational experimental orthogonal function(REOF)*** results show that the TP is an isolated heating source in this *** lagged correlation analysis between the first rotational principal component(RPC)of SH over the TP in May and rainfall of EA in July demonstrates that strong SH over the TP before July leads to a positive rainfall anomaly over the TP,the valley between the Yangtze River and Huaihe River,and the regions south and southeast of the TP,and the Sichuan Basin and Yunnan-Guizhou Plateau,but less rainfall anomaly over the regions north,northeast,and west of the *** rainfall anomaly patterns are shown to be well coordinated with those of the circulation and vapor flux fields,and are explained by using the thermal adaptation theory and quasi-stationary large-scale vorticity ***,the status of SH over the TP during AMJ can be used as a predictor for the rainfall anomaly over EA,especially in the valley between the Yangtze River and Huaihe River.

关键词： Tibetan Plateau sensible heating East Asia rainfall circulation.

Conditional nonlinear optimal perturbation: Applications to stability, sensitivity, and predictability

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Science China Earth Sciences 2009年第7期52卷 883-906页

作者： DUAN WanSuo MU Mu State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

Conditional nonlinear optimal perturbation (CNOP) is a nonlinear generalization of linear singular vector (LSV) and features the largest nonlinear evolution at prediction time for the initial perturbations in a given constraint. It was proposed initially for predicting the limitation of predictability of weather or climate. Then CNOP has been applied to the studies of the problems related to predictability for weather and climate. In this paper, we focus on reviewing the recent advances of CNOP's applications, which involves the ones of CNOP in problems of ENSO amplitude asymmetry, block onset, and the sensitivity analysis of ecosystem and ocean's circulations, etc. Especially, CNOP has been primarily used to construct the initial perturbation fields of ensemble forecasting, and to determine the sensitive area of target observation for precipitations. These works extend CNOP's applications to investigating the nonlinear dynamical behaviors of atmospheric or oceanic systems, even a coupled system, and studying the problem of the transition between the equilibrium states. These contributions not only attack the particular physical problems, but also show the superiority of CNOP to LSV in revealing the effect of nonlinear physical processes. Consequently, CNOP represents the optimal precursors for a weather or climate event; in predictability studies, CNOP stands for the initial error that has the largest negative effect on prediction; and in sensitivity analysis, CNOP is the most unstable (sensitive) mode. In multi-equilibrium state regime, CNOP is the initial perturbation that induces the transition between equilibriums most probably. Furthermore, CNOP has been used to construct ensemble perturbation fields in ensemble forecast studies and to identify sensitive area of target observation. CNOP theory has become more and more substantial. It is expected that CNOP also serves to improve the predictability of the realistic predictions for weather and climate events play

关键词： optimal perturbation predictability stability sensitivity

Numerical simulation of viscous flow past an oscillating square cylinder using a CIP-based model

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Journal of Hydrodynamics 2017年第1期29卷 96-108页

作者：付英男赵西增曹飞凤张大可程都李莉 Ocean College Zhejiang University Shanghai Merchant ship Design and Research institute institute of Harbor-Channel and Coastal Engineering Department of Civil Engineering Zhejiang University of Technology State Key Laboratory of Satellite Ocean Environment dynamics Second Institute of Oceanography

The flow past an in-line forced oscillating square cylinder at Reynolds number of 200 is studied using an in-house code, named constrained interpolation profile method developed in Zhejiang University （CIP-ZJU）. The model is established in the Cartesian coordinate system using the CIP method to discretise the Navier-Stokes equations. The fluid-structure interaction is treated as a multiphase flow of the liquid and solid phases to be solved simultaneously. An immersed boundary method is used to deal with the boundary of the solid body. The CFD model is first applied to the computation of the flow past a fixed square cylinder for its validation. Computations are then performed for the flow past a square cylinder oscillating in the streamwise direction. Considerable attention is paid to the symmetric and anti-symmetric modes of the vortex shedding in the oscillating square cylinder wake. Various oscillation amplitudes and frequencies are simulated and their effects on the vortex shedding modes are analyzed via Lissajous patterns of the unsteady lift coefficient. The relationship among the lift coefficient, the drag coefficient and the lock-on range is also investigated quantitatively.

关键词： Flow past cylinder oscillating square cylinder lock-on CIP method immersed boundary method

Effect of HITRAN Database Improvement on Retrievals of Atmospheric Carbon Dioxide from Reflected Sunlight Spectra in the 1.61-μm Spectral Window

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Advances in Atmospheric Sciences 2012年第2期29卷 227-235页

作者：戴铁石广玉张兴赢 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences National Satellite Meteorological Center

A large number of experimental and theoretical investigations of carbon dioxide （CO 2 ） spectra have been conducted since the most recent update of the High-Resolution Transmission Molecular Absorption （HITRAN） database. To maintain optimal parameters, the HITRAN 2004 CO 2 line list has been completely replaced by HITRAN 2008 data in the near-infrared region from 4300 cm-1 to 7000 cm-1 . To examine the effect of this change on the retrieval of CO 2 vertical column data from reflected sunlight spectra in the 1.61-μm spectral window, synthetic measurements for a given atmospheric state and instrument setup were generated and compared using radiative transfer model with the line-transition parameters from the HITRAN 2004 and 2008 databases. Simulated retrievals were then performed based on the optimal estimation retrieval theory. The results show that large systematic errors in atmospheric CO 2 column retrievals were induced by the differences in the HITRAN laboratory line parameters in the 1.61-μm region. The retrieved CO 2 columns were underestimated by 10 ppm using the HITRAN 2004 data, and improvements resulting from the use of the improved HITRAN database were more pronounced at a higher spectral resolution.

关键词： HITRAN database retrieval of CO 2 reflected sunlight spectra

ACOUSTOELASTIC theory FOR fluid-SATURATED POROUS MEDIA

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Acta Mechanica Solida Sinica 2014年第1期27卷 41-53页

作者： Huaqing Wang Jiayong Tian institute of Crustal dynamics China Earthquake Administration

Based on the finite deformation theory of the continuum and poroelastic theory, the aeoustoelastic theory for fluid-saturated porous media （FSPM） in natural and initial coordi- nates is developed to investigate the influence of effective stresses and fluid pore pressure on wave velocities. Firstly, the assumption of a small dynamic motion superimposed on a largely static pre- deformation of the FSPM yields natural, initial, and final configurations, whose displacements, strains, and stresses of the solid-skeleton and the fluid in an FSPM particle could be described in natural and initial coordinates, respectively. Secondly, the subtraction of initial-state equations of equilibrium from the final-state equations of motion and the introduction of non-linear constitu- rive relations of the FSPM lead to equations of motion for the small dynamic motion. Thirdly, the consideration of homogeneous pre-deformation and the plane harmonic form of the small dynamic motion gives an acoustoelastic equation, which provides analytical formulations for the relation of the fast longitudinal wave, the fast shear wave, the slow shear wave, and the slow longitudinal wave with solid-skeleton stresses and fluid pore-pressure. Lastly, an isotropic FSPM under the close-pore jacketed condition, open-pore jacketed condition, traditional unjacketed condition, and triaxial condition is taken as an example to discuss the velocities of the fast and slow shear waves propagating along the direction of one of the initial principal solid-skeleton strains. The detailed discussion shows that the wave velocities of the FSPM are usually influenced by the effective stresses and the fluid pore pressure. The fluid pore-pressure has little effect on the wave velocities of the FSPM only when the components of the applied initial principal solid-skeleton stresses or strains are equal, which is consistent with the previous experimental results.

关键词： acoustoelasticity fluid-saturated porous media wave velocity the effective stress fluid pore pressure