含正多边形纳米孔次生多裂纹的一维六方压电准晶体的反平面剪切问题

利用Gurtin-Murdoch表界面理论和复势法,讨论一维六方压电准晶体含纳米级正n边形孔口次生多裂纹的反平面问题,得到电场、声子场和相位子场强度因子和能量释放率的精确解。通过算例讨论纳米级孔口次生裂纹形貌对能量释放率和场强度因子的影响。结果显示：当缺陷达到纳米尺寸时,在声子场、相位子场和电场相互耦合作用下会产生表面效应,缺陷尺寸越小表面效应越明显,裂纹条数越多场强度因子越小,随着缺陷尺寸的变大,表面效应的影响会逐渐减弱,最后趋于经典断裂理论的结果。     

Heat transfer during bubble formation

The flow around a gas bubble forming at a submerged orifice without vaporisation is analysed both with and without heat transfer taking place from the bubble surface. The results of experiments are given in which high-speed photography was used to study air bubbling through four different sizes of orifice into water, for the isothermal and diabatic case. A numerical solution of the dimensionless equations using Hamming's modified predictor-corrector method gave excellent agreement with experimental measurements of the bubble volume-time history for both stages of growth as well as predicting accurately the transition point between the two stages. Most of the heat transfer was found to occur almost immediately after the start of bubble growth     

可渗透圆柱壳流固耦合问题的流场与内力分析

在弹性薄壳的非线性理论和流体力学基本方程的基础上,研究了可渗透圆柱壳的流固耦合问题.假定壳体具有均布孔隙且孔的面积很小,不考虑其阻力,忽略对弯曲刚度和壳体腔内流体微小运动影响,应用相容欧拉--拉格朗日法建立了带孔的圆柱壳在流体中相互作用的基本方程.通过具体算例求解,给出了流场速度与压力的变化、圆柱壳的变形及内力分布,并对相关参数进行了讨论.