Lei Huan, Baker Nathan A, Wu Lei, Schenter Gregory K, Mundy Christopher J, Tartakovsky Alexandre M
Pacific Northwest National Laboratory, Richland, Washington 99354, USA.
LMAM and School of Mathematical Sciences, Peking University, Beijing 100871, China.
Phys Rev E. 2016 Aug;94(2-1):023304. doi: 10.1103/PhysRevE.94.023304. Epub 2016 Aug 5.
Thermal fluctuations cause perturbations of fluid-fluid interfaces and highly nonlinear hydrodynamics in multiphase flows. In this work, we develop a multiphase smoothed dissipative particle dynamics (SDPD) model. This model accounts for both bulk hydrodynamics and interfacial fluctuations. Interfacial surface tension is modeled by imposing a pairwise force between SDPD particles. We show that the relationship between the model parameters and surface tension, previously derived under the assumption of zero thermal fluctuation, is accurate for fluid systems at low temperature but overestimates the surface tension for intermediate and large thermal fluctuations. To analyze the effect of thermal fluctuations on surface tension, we construct a coarse-grained Euler lattice model based on the mean field theory and derive a semianalytical formula to directly relate the surface tension to model parameters for a wide range of temperatures and model resolutions. We demonstrate that the present method correctly models dynamic processes, such as bubble coalescence and capillary spectra across the interface.
热涨落会导致多相流中流体-流体界面的扰动以及高度非线性的流体动力学。在这项工作中，我们开发了一种多相平滑耗散粒子动力学（SDPD）模型。该模型既考虑了体相流体动力学，也考虑了界面涨落。界面表面张力通过在SDPD粒子之间施加成对力来建模。我们表明，先前在零热涨落假设下推导的模型参数与表面张力之间的关系，对于低温流体系统是准确的，但对于中等和较大热涨落会高估表面张力。为了分析热涨落对表面张力的影响，我们基于平均场理论构建了一个粗粒化欧拉晶格模型，并推导了一个半解析公式，以在广泛的温度和模型分辨率范围内直接将表面张力与模型参数联系起来。我们证明了本方法能够正确地模拟动态过程，如气泡聚并和跨界面的毛细光谱。
