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831.
In order to study cross flow induced vibration of heat exchanger tube bundles, a new fluid–structure interaction model based on surface vorticity method is proposed. With this model, the vibration of a flexible cylinder is simulated at Re=2.67 × 104, the computational results of the cylinder response, the fluid force, the vibration frequency, and the vorticity map are presented. The numerical results reproduce the amplitude‐limiting and non‐linear (lock‐in) characteristics of flow‐induced vibration. The maximum vibration amplitude as well as its corresponding lock‐in frequency is in good agreement with experimental results. The amplitude of vibration can be as high as 0.88D for the case investigated. As vibration amplitude increases, the amplitude of the lift force also increases. With enhancement of vibration amplitude, the vortex pattern in the near wake changes significantly. This fluid–structure interaction model is further applied to simulate flow‐induced vibration of two tandem cylinders and two side‐by‐side cylinders at similar Reynolds number. Promising and reasonable results and predictions are obtained. It is hopeful that with this relatively simple and computer time saving method, flow induced vibration of a large number of flexible tube bundles can be successfully simulated. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
832.
Transport in Porous Media - 相似文献
833.
Claude A. Pruneau 《Acta Physica Hungarica A》2004,21(2-4):261-266
We present analyses of event-by-event dynamical net charge fluctuations measured in 130 and 200 GeV Au+Au collisions with the STAR detector. The dynamical net charge fluctuations are evaluated using the ν +-,dyn observable. Dynamical fluctuations measured in Au+Au collisions at 130 and 200 GeV are finite, and exceed charge conservation limits. They deviate from a perfect 1/N scaling and provide an indication that the collision dynamics varies with collision centrality. 相似文献
834.
835.
Backscattered-particle production is studied by means of a detailed simulation of cascade processes in a dense medium. The energy dependence of the albedo and the spatial and angular distributions of various components of this flux are analyzed. 相似文献
836.
A. N. Enyashin V. V. Ivanovskaya Yu. N. Makurin A. L. Ivanovskii 《Physics of the Solid State》2004,46(8):1569-1573
A comparative analysis of the stability factors and electronic structure of two possible crystalline forms of small fullerene C28 and endohedral fullerene Zn@C28 with diamond and lonsdaleite structures is performed using a cluster model. Atoms of elements that, when placed inside C28 cages, have no significant effect on the stability of free small-fullerene molecules are shown to be able to dramatically change the electronic properties and reactivity of the C28 skeleton and to be favorable for forming small-fullerene crystalline modifications, which are covalent crystals. In contrast, if the presence of foreign atoms inside C28 cages stabilizes the isolated nanoparticles, then molecular crystals (such as C60 fullerites) are formed due to weak van der Waals forces. 相似文献
837.
A method is proposed for constructing appropriate sets of special points in the Brillouin zone in which the extended unit cell method is used with a subsequent shift from the center of the reduced Brillouin zone. The proposed method offers several advantages over the commonly used Monkhorst-Pack method. The difference in the construction of sets of special points for the direct and reciprocal lattices is discussed for crystals belonging to a nonsymmorphic space group. The cases of a planar square lattice and an fcc lattice are considered to illustrate general results. 相似文献
838.
M. A. Zelikman 《Technical Physics》2004,49(4):379-387
An analytical method for evaluating the Josephson and magnetic energies of a vortex, as well as the vortex pinning energy
and its components, in a long periodically modulated Josephson contact is suggested. The method allows one to take into account
the variation of the vortex shape with the position of the vortex. The results obtained with this method are much closer to
those of exact computer analysis compared with results of the conventional techniques. The discrepancy between the exact shape
of the vortex and a function obtained by solving a differential equation approximating the exact difference equation is studied. 相似文献
839.
Electric and spatial characteristics of a pulse-periodic microsecond barrier discharge are investigated in different geometries—triangular
prism, plate, and corrugated electrode—that are in contact with a dielectric plate and form a dihedral angle with it. It is
established that, in the space of the dihedral angle, the regions of discharge represent alternating cylindrical layers with
the axes lying on the contact line. The first conducting layer is formed at some distance from the contact edge of the electrode.
The number of layers and their localization are determined by the angle formed between an electrode and the dielectric plate.
A physical model explaining the main features of the structure formation is proposed. 相似文献
840.
In the present paper, the methods of x-ray diffractometry are used to investigate the influence of plastic deformation on the long-range atomic order in alloys with L12, L12(M), and L12(MM) superlattices. The influence of ordering energy, initial values of the long-range order parameter, and average sizes of antiphase domains on the specific features of the dependence of long-range order parameter on the strain degree is considered. It is demonstrated that the wetted strain-induced order-disorder phase transition occurs with rapid accumulation of antiphase boundaries that play an important role in the destruction of long-range atomic order.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 21–32, September, 2004. 相似文献