Dissipative Particle Dynamics Simulation Of Multipahse Separation And Liquid-vapor Coexistence

In the domain of complex multiphase flow, multiphase separation and liquid-vaporcoexistence are one of important branches, applied widely in many engineering field.Multiphase flow is more complex than one-phase flow. The main reasons are these:each phase has its property, interface between different phase would change greatly,transfer of mass and energy exists interfaces which are always in nonequilibrum.The dissipative particle dynamics (DPD) technique is a relatively new mesosclaetechnique which was initially developed to simulate hydrodynamic behavior inmesoscopic complex fluids. It is essentially a particle technique in which interfaces areeasily captured. Many body dissipative particle dynamics (MDPD) simulation is a novelpromising mescopic method to model the liquid-vapor interface, the difference betweenDPD and MDPD lies in that the later improves conservative force.By using DPD and MDPD method, multiphase separation, droplets formation inliquid-vapor coexistence system with microgravity and without gravity are simulatedcomprehensively. Two benchmark in flow are tested: Poiseuille flow and shear flow.Different boundary methods are implemented to gain a better non-slip boundarycondition. The process of multiphase separation and mix are implemented dynamically.interface tension increases as the conservative interactions between different DPDparticles increase, and these results following are verified: interface tension decrease astemperature increases, one key factor to mantain stable interface is interface tension.MDPD has the ability to capture the mechanisms at the mesoscopic scale thoughcoalescence of a droplet on different surface. The process of droplets formation insystem with microgravity and without gravity are implemented dynamically, density,temperature and pressure through center of droplets are calculated. The influence ofwall to droplets is researched.