Effects of Viscosity on Bead Shape of Polydimethylsiloxane Fluid Flowing down a Fiber VICTORIA GERSHUNY JEFF WALTER AND AMMON WASHBURN

Motivation  Effectiveness of:  Removal of pollutants from a fluid  Saturation of liquid with gas  Transport of materials through slurry flow Slurry flow - transport-velocity-d_236.html

Previous studies  Mean velocity of the fluid flowing down a fiber increases, the mean minimum and maximum droplet diameter increase, (Friedman & Miller 1941; Gr¨unig et al. 2013, 2010).  Mean velocity is greater as liquid flow rate increases, (Gr¨unig et al. 2010).  Greater fiber diameter leads to greater bead diameter, (Gr¨unig et al. 2013).  Distance from the inlet of the fluid increases, the fluid velocity increases, (Wehinger et al. 2013).

Layers of fluid  Boundary layer - closest to the fiber  Internal layers - surrounded by fluid  Outer layer - in contact with the air Forces  Boundary layer - adhesion to the fiber, gravity, and shearing from the adjacent layer  Internal layers - gravity and shearing from adjacent layers on both sides of the fluid  Outer layer - gravity, shearing from one adjacent layer, and negligible adhesion to the air particles

Interaction Between Different Forces

Experimental Set-Up

Measurements  Steady state - moment when the distance between drops was at a minimum with respect to time  Measurements:  Minimum bead diameter  Maximum bead diameter  Bead to bead separation

Bead Shape

Min and Max Diameter

Distance Between Beads  1000 cst could not be included because of non reliability  Three neighboring drops at steady state had a 47.2% difference in their separation

Velocity

Reynolds Number  WE NEED TO FILL THIS IN BUT I DON’T HAVE THE MOST RECENT VERSION SO IM NOT SURE WHAT TO SAY

Conclusions  Bead diameter and the difference between the minimum and maximum bead diameter increased for increased viscosity  Minimum bead diameter did not vary significantly  Viscosity affected the inner layers of fluid, but did not significantly affect the boundary layers  Bead separation decreased with increased viscosity  Reynolds number decreased with increased viscosity

Future Studies  Collect data closer to inlet  Measure fluid velocity experimentally  Use a wider range of viscosities

References  Crowe, C. T., J. D. Schwarzkopf, M. Sommerfeld, and Y. Tsuji. Multiphase flows with droplets and particles. 2nd ed. Boca Raton, FL: CRC Press, Print.  Friedman, S. J., and C. O. Miller. "Liquid films in the viscous flow region. "Industrial & Engineering Chemistry 33.7 (1941):  Grünig, J., S ‐ J. Kim, and M. Kraume. "Liquid film flow on structured wires: Fluid dynamics and gas ‐ side mass transfer." AIChE Journal 59.1 (2013):  Grünig, J., T. Skale, and M. Kraume. "Liquid flow on a vertical wire in a countercurrent gas flow." Chemical Engineering Journal (2010):  Hattori K, Ishikawa M, Mori YH. Strings of liquid beads for gas-liquid contact operations. AIChE J. 1994;40:1983–1992.  Munson, Bruce Roy, and T. H. Okiishi. Fundamentals of fluid mechanics. 6th ed. Hoboken, NJ: J. Wiley & Sons, Print.  Sigma Aldrich. “Silicone oil.” Dow Corning Corporation: Midland, Michigan,  Smolka, Linda B., Justin North, and Bree K. Guerra. "Dynamics of free surface perturbations along an annular viscous film." Physical Review E 77.3 (2008):  Wehinger, Gregor D., et al. "Numerical simulation of vertical liquid-film wave dynamics." Chemical Engineering Science 104 (2013):

Thank you for listening And a thank you to Dr. Tabor and Bob Reinking