دانلود پایان نامه کارشناسی ارشد انگلیسی دربارۀ مطالعه عددی تشکیل قطره به روش لتیس-بولتزمن Lattice Boltzmann Method

Liquid droplets are widely used as reaction media for the chemical manipulation of cells. The droplet formation and cell encapsulation process involves multiphase flows along with coupled cell membrane-fluid mechanics. In this study, the droplet formation behavior in a T-shaped micro-fluidic device is simulated using two- and three-dimensional lattice Boltzmann method (LBM). With the adoption of pseudo potential model, the LBM can accomplish the accurate tracking of the liquid-liquid or liquid-gas interface automatically. The two-dimensional simulation results agree favorably with experimental results in the aspects of droplet length and the droplet shapes before and after the breakup. For the two-dimensional cell model, the effects of the two important dimensionless parameters, the shear rate and the reduced ratio of bending to elasticity moduli, are investigated systematically. The deformation of the cell in the process of cell encapsulation is found to have close relation with the local flow flied. Surprisingly, it is found that, the cell is still experiencing the force from the surrounding fluid even when the steady transportation of the cell has started after it has been capsulated in a droplet. In the three-dimensional simulations, three regimes of droplet formation are clearly identified as the capillary number increases from 0.002 to 0.056. The previously known four stages of squeezing regime are reproduced.