液气共存的耗散粒子动力学模拟

Simulation of vapor-liquid coexistence using dissipative particle dynamics

传统的耗散粒子动力学方法(DPD)由于采用了纯排斥的守恒力相互作用,从而不能适应液气共存或者带有自由面流体的模拟.这里研究了DPD方法中新近提出的一种短程排斥、长程吸引相互作用,探索了这种改进势能对于DPD方法模拟液气共存的能力.模拟了这种新势能所形成的液气过渡界面,计算了过渡界面区的应力分布,发现应力分布与多体DPD方法所得结果一致.进一步对表面张力进行了研究,验证了这种势能所形成的界面满足Laplace定律,而通过理论公式与Laplace定律分别所得到的表面张力也彼此相符。

Due to a purely repulsive conservative interaction adopted in the traditional dissipative particle dynamics,the vaporliquid coexistence phenomena or fluid flows with free surfaces could not be simulated.In the present study a recently proposed combination of short-range repulsive and long-range attractive interaction for DPD was investigated to explore its ability of simulating vapor-liquid coexistence or fluid flows with free surfaces.With this modified interaction,steady vaporliquid interface could be obtained in DPD simulation,and the stress distribution across the vapor-liquid interface region was also discussed,which were found in accordance with those obtained by multibody DPD.Furthermore,surface tension of vapor-liquid interface was studied,and it was verified that Laplace＇s law is satisfied in our simulation.Surface tensions obtained by theoretical method and Laplace＇s law,respectively,are in agreement with each other.