Fingering instability down the outside of a vertical cylinder

We present an experimental and numerical study examining the dynamics of a gravity-driven contact line of a thin viscous film traveling down the outside of a vertical cylinder of radius R. Experiments on cylinders with radii ranging between 0.159 and 3.81 cm show that the contact line is unstable to a fingering pattern for two fluids with differing viscosities, surface tensions, and wetting properties. The dynamics of the contact line is studied and results are compared to previous studies of inclined plane experiments in order to understand the influence substrate curvature plays on the fingering pattern. A lubrication model is derived for the film height in the limit that ε = H/R≪1, where H is the upstream film thickness, and in terms of a Bond number ρgR3/(γH), and the linear stability of the contact line is analyzed using traveling wave solutions. Curvature controls the capillary ridge height of the traveling wave and the range of unstable wavelength when ε = O(10-1), whereas the shape and stability of the contact line converge to the behavior one observes on a vertical plane when ε ≤ O(10-2). The most unstable wave mode, cutoff wave mode for neutral stability, and maximum growth rate scale as 0.45 where = ρgR2/γ ≥ 1.3, and the contact line is unstable to fingering when ≥ 0.56. Using the experimental data to extrapolate outside the range of validity of the thin film model, we estimate the contact line is stable when <0.56. Agreement is excellent between the model and the experimental data for the wave number (i.e., number of fingers) and wavelength of the fingering pattern that forms along the contact line.

Burning Skies: A Novella

Burning Skies is a seventy-page novella completed as an Honors Thesis in Creative Writing. The story is set in Los Angeles, California, during the 1992 riots surrounding the controversy over the beating of Rodney King by four white police officers. The story is toldthrough the perspectives of the four main characters: Erin, a woman who is four months pregnant with a baby she desperately wants; her husband David, who has moved the couple out to California so that he can pursue his dream of being a cinematographer; Abby, David’s deeplyreligious younger sister who has unexpectedly flown out to Los Angeles from her home in Indiana after discovering her husband’s infidelity; and Cameron, a black man training to be a pastor who Abby has befriended through her years of missionary work in Los Angeles.The novella follows the events of the riots as they break out all across the city and the personal dramas of each of the four main characters, looking at how the public interacts with theprivate and examining the ways in which explosions in the public and political sphere can ricochet into our private and personal lives. It is a story about the political and racial climate in Los Angeles in the early 1990s, but it is also a story about four human beings, about their needs and their desires, about their struggles to survive in an unpredictable world. The novella showcases the skills and techniques the author has learned after four years of studying fiction at Bucknell University; it can best be described as a work of realistic fiction.