Parametric study of the shock driven multiphase flow
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This thesis presents a study of the shock driven multiphase instability and explores the competing effects of particle and gas effects in mixing. Eight different simulations were carried out to study properties of the particle-gas system based on various particle concentrations, particle sizes, and gas densities. Each case uses the surrounding gas as air in the shock tube and the incident Mach number is 1.66 with four different sets of gas and particle Atwood number (density ratios) combinations. These combinations are linked with two particle sizes. Two different domains are considered on the basis of the maximizing resolution for the available computational resources provided by Lewis, the University of Missouri supercomputer. For deciding the resolution, zones across the diameter of the interface are calculated and then highest resolution achievable was chosen for the analysis It is shown that both gas and particle properties influence mixing. Comparison of the density contours of all eight cases shows the sudden increase in the density due to evaporative cooling from the particles. Plots of tagged gas and particle position highlight the momentum lag behavior of the particles and show the interface evolution. The particle evaporation effect and the effect of strong gas Atwood number is shown to drag particles to the tail of the interface at a later time, increasing mixing. The difference in the particle enstrophy due to variation in the particle size shows the opposite behavior at an initial time to the late time. The effects of evaporation of particles in the vapor contours are more evident in the small-sized particles showing increased vapor mass fraction at the late times inside the cores of the vortices. At last, the particle mixing width and the vapor mixing width were plotted to qualitatively define the particle lag behavior. These show a complex correlation between the particle and tagged gas fields across different parametric combinations.
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