检索结果-南通市图书馆

Role of grain boundary networks in vortex motion in superconducting films

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2023年第12期32卷 528-533页

作者：刘宇薛峰苟晓凡 College of Mechanics and Materials Hohai UniversityNanjing 211100China

We study the vortex dynamics of the polycrystalline superconductors in the presence of both random point defects and the generated grain boundary(GB) networks with Voronoi diagram. The synergistic effect of adjacent GBs on restricting the vortex motion in intragranular region is proposed and the corresponding intensity factor of the synergistic effect which characterizes the strength of the synergistic restriction of adjacent grain boundaries is also determined in the present *** interconnected GBs offer easy-flow channels for vortices in addition to pinning effects on the vortices. The combined channels and the vortex flow patterns in the superconducting film are analyzed in detail from molecular dynamics simulations. Furthermore, it is discovered that the critical current increases with the decrease of magnetic field intensity,temperature, and the average grain size. The large number of vortices results in the enhanced repulsive interaction forcing the vortices to move out from the GBs. The thermal depinning from GBs leads to the lower Lorentz force range. The increase of the grain size causes the number of GBs to decrease. In summary, these effects leads the critical current to become a decreasing function of magnetic field, temperature, and grain size.

关键词： grain boundary network Voronoi tessellation synergistic effect intensity factor of synergistic effect vortex motion combined channels

A NUMERICAL STUDY OF THE vortex motion IN OSCILLATING FLOW AROUND A CIRCULAR CYLINDER AT LOW AND MIDDLE Kc NUMBERS

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 1994年第3期10卷 212-219页

作者：凌国平凌国灿 Dept.of Mathematics Suzhou UniversitySuzhou 215006China LNM Institute of MechanicsAcademia SinicaBeijing 100080China

A new hybrid model, which is based on domain decomposition and proposed by the authors is used for calculating the flow around a circular cylinder at low and middle Keulegan-Carpenter numbers (Kc=2～18)*** vortex motion patterns in asymmetric regime,single pair(or transverse)regime and double pair(or diagonal)regime are successfully *** calculated drag and inertial force coefficients are in better agreement with experimental data than other recent computational results.

关键词： oscillating flow separated flow vortex motion domain decomposition hybrid method finite difference method vortex method

Modeling three-dimensional dynamic stall

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2011年第4期32卷 393-400页

作者：吕超王同光 Jiangsu Key Laboratory of Hi-Tech Research for Wind Turbine Design Nanjing University of Aeronautics and Astronautics

The dynamic stall process in three-dimensional （3D） cases on a rectangular wing undergoing a constant rate ramp-up motion is introduced to provide a qualitative analysis about the onset and development of the stall phenomenon. Based on the enhanced understanding of the mechanism of dynamic stalls, a 3D dynamic stall model is constructed with the emphasis of the onset, the growth, and the convection of the dynamic stall vortex on the 3D wing surface. The results show that this engineering dynamic stall model can simulate the 3D unsteady aerodynamic performance appropriately.

关键词： unsteady flow 3D dynamic stall separation flow vortex motion

STUDY　OF　INTERACTION　BETWEEN　VORTICES　AND　A　FREE　SURFACE　PART　Ⅱ：INTERACTION　OF　DOUBLE　VISCOUS　vortex　DIPOLES　WITH　A　FREE　SURFACE

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 1995年第1期7卷 17-32页

作者： Wu Chui-jie Tan Bo-yan (Air Force Institute of Meteorology,Nanjing 211101 P. R. China)Ma Hui-yang(Graduate School of Academia Sinica, Beijing 100039 P. R. China)( Air Force Inst of Meteorology Nanjing China

In this paper the VOF (Volume of Fluid) method is used to numerically study the interaction of double viscous vortex dipoles with free surface in a two dimensional incompressible flow field. From the results of this research, it is found that the general consequence of the interaction is qualitatively equivalent to the problem of a single vortex dipole interacts with a free surface.

关键词： vortex motion free surface computational fluid mechanics.

NUMERICAL　STUDY　ON　THE　vortex　STRUCTURES　IN　THE　WAKE　OF　AN　OSCILLATING　CIRCULAR　CYLINDER　IN　A　UNIFORM　FLOW

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 1994年第1期6卷 12-22页

作者： Lu Xi-yun Tong Bing-gang Zhuang Li-xian Yin Xie-yuan (Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230026,P. R. China) Univ of Science and Technology of China Hefei China

vortex shedding from a circular cylinder subjected to fortal oscillations at arbitrary angles(as shown in Fis. 1 for 0°<β<90°) with respect to the free stream is numerically investigated using the Navier-Stokes equ... 详细信息

vortex shedding from a circular cylinder subjected to fortal oscillations at arbitrary angles(as shown in Fis. 1 for 0°vortex structures and their evolution in the near wake. In the present study, a number of possible vortex modes are also numerically simulated, and a variety of physical phenomena are duplicated and even renewed numerically. A parameter map indicating the classification of preferred vortex modes is firstly given in the frequency-amplitude plane.

关键词： unsteady flow vortex motion separated flow oscillatory flow.

motion ANALYSIS OF A SPINNING SATELLITE SYSTEM WITH OFF-CENTRE TANKS PARTIALLY FILLED WITH LIQUID

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 1989年第3期5卷 269-277页

作者： Wang Zhaolin Liao Min Deng Zhongping(Department of Engineering Mechanics,Tsinghua University) Department of Engineering Mechanics Tsinghua University Tsinghua China

The sloshing problem for a spherical tank partially filled with liquid is analysed in this paper The study is based on the goveming equations of fluid dynamics and the Euler's equations of systems with the influences of tank off centering,fluid vortices and the Coriolis'acceleration on the motion states of the systems taken into *** the study,we adopt the concept of uniform vortex motion of fluid gen- eralized by Pfeiffer and apply the boundary element method(BEM)to the calculation of the natural frequence and the velocity field of the liquid *** motion charateristics of the flow-solid spinning system is then analysed.

关键词： liquid sloshing fluid-solid coupling liquid-filled satellite vortex motion

Chaotic movement of vortices in superconductors of high-T_c superconducting maglev system at a high speed

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Transportation 2012年第2期20卷 70-75页

作者： H.T. LIN Department of Information Management Department of Electrical Engineering Cheng Shiu University Taiwan China

vortex motion in superconductors of high-To superconducting maglev system is studied by a computational simulation. The vortex system is treated in a similar fashion, as a system where defects are arranged in periodic arrays and driven by an alternating current （AC） field. Computational simulation reveals that due to the high nonlinearity of the vortex-defect interaction, the system shows typical chaotic characters. Effects of the vortex-vortex coupling, the driving frequency, and the vortex viscosity on the vortex motion have been studied to reveal the interaction between the spatial and temporal chaos. It is found that the mean-field approach is a good approximation to describe the vortex motion in one dimensional vortex system under an AC driving field. The vortex motion under the damping mode is a kind of self-organized motion. Lastly, the spatial chaos can dominate the chaotic behavior of the system.

关键词： superconductors vortex motion spatial chaos temporal chaos

vortex-Wave Interaction on a Sphere

在线全文

学校读者我要写书评

暂无评论

Vortex-Wave Interaction on a Sphere