J053031 Lennard-Jones流体の粗視化に基づく散逸粒子動力学相互作用モデルの構築 : 気液界面を含む系に関する検討

Abstract

The application of molecular dynamics (MD) simulation to mesoscale (10-100 nm) flow analysis is computationally expensive at present. Dissipative particle dynamics (DPD) simulation is the powerful candidate for the alternative method. Larger scale and longer time simulation is possible by using DPD since a single dissipative particle represents multi-particles. In DPD interaction models, the force contains three parts, each of which is pairwise additive: conservative, dissipative and random forces, respectively. In the conventional DPD framework, the parameters of these three forces are determined so that macroscopic properties such as diffusivity or compressibility are recovered. In our study, we investigate the method of bottom-up construction of DPD models by means of MD simulations. We focus on the center of mass of the cluster containing Lennard-Jones (LJ) particles and extract the effective forces exerted on the clusters. In our simulations, the DPD model can roughly reproduce the surface tension of the MD system while the temperature and diffusivity are underestimated due to the overestimation of friction coefficients. The diffusivity of the DPD system can be improved by scaling the friction coefficients so that the temperature of the DPD system matches that of the MD system.