Ching-Yao Lai (graduate student), Zhong Zheng (postdoc), Jason S. Wexler (graduate student alumnus), and Howard A. Stone (faculty)
Department of Mechanical and Aerospace Engineering
In fracking, or hydraulic fracturing, high-pressure fluid cracks rock in the earth’s crust, releasing natural gas that is then collected. This technique has received much attention in recent years due to its potential to provide a new source of fossil fuels, but also because many aspects of fracking are poorly understood. Our goal in this experiment is to better understand the shape taken by a hydraulically generated crack. In particular, does the crack grow like tree branches; does it form intersecting surfaces; or is the shape random? We chose to frack gelatin, the main ingredient in Jello, since it is transparent and, for the purposes of mechanical modeling, has similar brittle properties to the rock in the earth’s crust. By injecting liquid mixed with fluorescent dye from a needle placed in the middle of a cube of gelatin, we visualize the beautiful dynamics of the process of crack generation.