Nugent S, Posch HA
Institut fur Experimentalphysik, Universitat Wien, Boltzmanngasse 5, A-1090 Wien, Austria.
Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 2000 Oct;62(4 Pt A):4968-75. doi: 10.1103/physreve.62.4968.
Smoothed particle applied mechanics (SPAM), also referred to as smoothed particle hydrodynamics, is a Lagrangian particle method for the simulation of continuous flows. Here we apply it to the formation of a liquid drop, surrounded by its vapor, for a van der Waals (vdW) fluid in two dimensions. The cohesive pressure of the vdW equation of state gives rise to an attractive, central force between the particles with an interaction range which is assumed to exceed the interaction range of all the other smoothed forces in the SPAM equations of motion. With this assumption, stable drops are formed, and the vdW phase diagram is well reproduced by the simulations. Below the critical temperature, the surface tension for equilibrated drops may be computed from the pressure excess in their centers. It agrees very well with the surface tension independently determined from the vibrational frequency of weakly excited drops. We also study strongly deformed drops performing large-amplitude oscillations, which are reminiscent of the oscillations of a large ball of water under microgravity conditions. In an appendix we comment on the limitations of SPAM by studying the violation of angular momentum conservation, which is a consequence of noncentral forces contributed by the full Newtonian viscous stress tensor.
光滑粒子应用力学（SPAM），也被称为光滑粒子流体动力学，是一种用于模拟连续流动的拉格朗日粒子方法。在此，我们将其应用于二维范德瓦尔斯（vdW）流体中由其蒸汽包围的液滴形成过程。vdW状态方程的内聚压力在粒子之间产生一种吸引性的中心力，其相互作用范围被假定超过了SPAM运动方程中所有其他光滑力的相互作用范围。基于此假设，形成了稳定的液滴，并且模拟很好地再现了vdW相图。在临界温度以下，平衡液滴的表面张力可由其中心的压力过剩来计算。它与由弱激发液滴的振动频率独立确定的表面张力非常吻合。我们还研究了进行大幅度振荡的强烈变形液滴，这让人联想到微重力条件下一大团水的振荡。在附录中，我们通过研究角动量守恒的违反情况来评论SPAM的局限性，这是由完整牛顿粘性应力张量贡献的非中心力导致的结果。
