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231.
A Free-Lagrange CFD code is used to simulate the collapse of a cylindrical air cavity in water by a 1.9 GPa incident shock.
The Lagrangian treatment allows the air/water interface to be tracked throughout the interaction. The incident shock is partially
transmitted into the cavity, within which it experiences multiple reflections. The upstream cavity wall involutes to form
a high-speed jet which, on impact with the far cavity wall, produces an intense blast wave. Heating of the gas within the
cavity is highly non-isentropic, and is dominated by shock heating. The predicted final gas temperature is of order 12000
K, although the modelling assumptions used here lead to over-prediction of temperature during the later stages of collapse.
Received 14 September 1999 / Accepted 28 June 2000 相似文献
232.
We derive an equation for the acceleration of a fluid element in the spherical gravitational collapse of a bounded compact object made up of an imperfect fluid. We show that non-singular as well as singular solutions arise in the collapse of a fluid initially at rest and having only a tangential pressure. We obtain an exact solution of the Einstein equations, in the form of an infinite series, for collapse under tangential pressure with a linear equation of state. We show that if a singularity forms in the tangential pressure model, the conditions for the singularity to be naked are exactly the same as in the model of dust collapse. 相似文献
233.
Dimitar I. Dimitrov Andrey Milchev Kurt Binder Dieter W. Heermann 《Macromolecular theory and simulations》2006,15(7):573-583
Summary: Molecular dynamics simulations of a coarse‐grained bead‐spring model of flexible macromolecules tethered with one end to the surface of a cylindrical pore are presented. Chain length N and grafting density σ are varied over a wide range and the crossover from “mushroom” to “brush” behavior is studied for three pore diameters. The monomer density profile and the distribution of the free chain ends are computed and compared to the corresponding model of polymer brushes at flat substrates. It is found that there exists a regime of N and σ for large enough pore diameter where the brush height in the pore exceeds the brush height on the flat substrate, while for large enough N and σ (and small enough pore diameters) the opposite behavior occurs, i.e. the brush is compressed by confinement. These findings are used to discuss the corresponding theories on polymer brushes at concave substrates.
234.
引人综合粘度度量聚合物溶液的粘弹性,利用无限大地层达西定律,导出了粘弹性流体径向流的压力损失方程。采用数值方法研究了粘弹性流体在变截面孔隙模型中的阻力特性,结合实例分析了粘弹性流体径向流的压力损失随粘弹性的变化规律。研究结果表明,弹性效应是影响注入压力升高的一个重要因素。聚合物溶液的粘弹性越大,其在地层孔隙中的渗流阻力越大,弹性效应在增高注入压力中所占的份额也越大。增加地层渗透率、降低注入排量、减小聚合物溶液的粘弹性均有利于降低注入压力,提高注入能力,改善注入效果。 相似文献
235.
236.
ZHANYou-Bang ZHOUPing FUHao 《理论物理通讯》2004,42(6):932-936
Dynamic evolution of a mesoscopic Josephson junction (MJJ) interacting with excited even and odd coherent states is studied. It is shown that the supercurrent in MJJ exhibits both collapse and revival (CR) phenomenon and squeezing effect. It is also shown that the CR and squeezing of supercurrent are related to degree of excitation and average photon number. 相似文献
237.
The atomic dynamical properties in the system with competing k-photon and l-photon transitions are studied fully by means of quantum theory. We discuss the influences of the mode-mode competition, the relative competing strengths of the atom and the two-mode field, and the initial state of the system on the atomic dynamics. We show that the presence of the mode-mode competition can result in quite a periodical collapses-revivals of the atomic inversion and the increase of the initial photons of the system can lead to the collapse-revival phenomenon and prolong the revival time of the atomic inversion. 相似文献
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240.
孔隙压力作用下圆形巷道围岩的蠕变分析 总被引:4,自引:0,他引:4
在原有的岩土流变理论基础上,与渗流力学原理相结合,考虑孔隙压力及孔隙度在岩石蠕变过程中对于岩体变形的影响,在弹性解答的基础上,通过Laplace变换(对应性原理)得出解析解.在一定的假设条件下,利用弹性力学基本方程、蠕变方程及有效应力原理(Terzaghi有效应力方程),采用H-K体模型作为本构方程,将孔隙压力引入到围岩蠕变方程中.给出在孔隙压力作用下的蠕变曲线,并与不考虑孔隙压力和定孔隙压力条件下蠕变曲线相比,其更接近于实际. 相似文献