TJ940 : Experimental analysis of Newtonian drop Dynamics in viscoelastic media
Thesis > Central Library of Shahrood University > Mechanical Engineering > MSc > 2024
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In the present study, the shape and movement of Newtonian fluid droplets in a viscoelastic fluid media were examined to identify the physical phenomena that occur for Newtonian droplets rising in a viscoelastic medium. This research was conducted experimentally using high-speed camera imaging, followed by image processing. The fluids used for the droplet phase included three Newtonian oils with different viscosities, and the fluids used for the media phase included two viscoelastic Boger fluids (Boger 100 and Boger 400) and one Newtonian fluid. For Newtonian droplets moving in a Newtonian media, the deviation from the spherical shape is very small, and with increasing volume, the droplets take on a relatively flattened shape. The shape of Newtonian droplets moving in a viscoelastic media is significantly influenced by the elastic properties of the surrounding fluid. As the volume increases, they deviate from a spherical shape and become balloon-like. With an increase in the elastic properties of the environment, the droplets undergo more severe deformations, and at a critical volume, their rear becomes pointed, forming a tail. The length and thickness of these tails are highly dependent on the physical properties of the droplet and the surrounding fluid. Droplets with higher viscosity form thicker tails. The velocity-volume graph for Newtonian droplets rising in a Newtonian environment is entirely continuous, and as the droplet volume increases, its velocity gradually increases. On the other hand, for Newtonian droplets rising in a viscoelastic media, there is a critical volume at which the droplet's velocity increases sharply. For baxse oil droplets rising in a Boger 400 fluid environment, a 10% increase in droplet volume results in a 174% increase in velocity. This sharp increase in velocity creates a discontinuity in the velocity-volume graph of the droplets.
Keywords:
#Boger fluid #Newtonian droplet dynamics #Viscoelastic media #Velocity jump #Discontinuity. Keeping place: Central Library of Shahrood University
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