Motion Interface Tracking And Simulation For Gas-Liquid Two Phase-Flows Under Normal Gravity And Microgravity

Gas-liquid two phase flows are common problems in nature and industry processes, and the main problem in this kind of problems is howto deal with the tracking and simulation of the interface between the two phases. In this work, a numerical approach has benn developed to capture the interface of the gas-liquid two phase flows, and we have carried out the research on the fluid flow and moving interface in normal gravity and microgravity.The dissertation includes the follows:1. The concept of contact angle is introduced into the original level set method, and the simulation for the wetting phenomena is realized;2. The area conservation in the original level set method is improved by adding the second area conservation, and the area for the small broken part is greatly conserved;3. The repulsive phenomenon of the wall to the moving body near the wall is confirmed. The effects of the Re number, density ratio, viscosity ratio and We number on the single, double droplets are studied in regular computational domains;4. The effects of the Re number, density ratio, viscosity ratio and We number on the single, double droplets near the wall are studied using multi level set functions in irregular computational domains;5. The effects of the Re number, density ratio, viscosity ratio, We number and frequency of g-jitter on the moving bubble near the wall are studied by considering g-jitter in microgravity, and the phenomena of wall attraction to the bubble near it is confirmed for the first time.Base on our large amount of numerical results, the following conclutions are drown:1. The research on the breaking dam indicates that the interface moving speeds are different when the contact angles of the interface are different, and the numerical results agree well with those of the experiments when θ=600;2. The research on falling droplets indicate that Re number affects the droplet falling speed, and the We number affects the deformation of the falling droplet;3. The area conservation can be up to0.4%and the area researvation has been improved greatly;4. The study on the bubble motion near the wall shows that the attractive force of the wall is related with the bubble initial position, density ratio, viscosity ratio, We number, and frequency of g-jitter, and the attractive phenomenon may disappear completely when the bubble is located initially too near or far from the wall.