Browsing by Subject "Surface tension"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item The Effect of Surface Tension in Modeling Interfacial Fracture(University of Minnesota. Institute for Mathematics and Its Applications, 2010-07) Sendova, Tsvetanka; Walton, Jay R.Item The Mechanism of Foaming in Deep-Pit Swine Manure Storage(2016-10) Yan, MiPork production is one of the most important agricultural activities in the United States, accounting for about $20 billion sales in 2011. Swine farms in upper Midwestern states of Minnesota, Iowa and Illinois are primarily designed with deep pit storage of manure under the pig barns, and manure is pumped out of these barns one to two times per year for land application. In recent years, it has been observed that a layer of foam would unexpectedly develop on the manure surface that is stored in these pits. This manure foaming has becomes a growing concern in the US swine industry because it traps a significant amount of methane gas, which is explosive under relatively high concentration, causing incidents of swine worker injuries and massive loss of living pigs by barn explosions and flash fires. No specific strategy has been developed to prevent the foaming and some swine producers are adding anti-foaming agents to provide a short term solution to prevent flash fires and explosions. Since no explanation of this manure foaming has been published, this study hypothesized several theories and then conducted related research. One hypothesis is that filamentous bacteria, which are considered the reason of foaming in municipal wastewater treatment systems, are the cause of this problem. Another hypothesis is that dried distillers grains with solubles (DDGS), an ethanol production by-product that is replacing corn and soybean in pig’s diet, are the cause of this problem. To verify these two hypotheses, microbial identification and chemical property analysis were carried out on different manure samples. This study provides experimental results to test these hypotheses, and more importantly provides ideas for the mitigation of the foaming issue. The research is expected to save labor and costs in the control of manure pit, and provide a safe environment for swine producer working and pigs living in these barns.Item Stress-driven melt segregation and reactive melt in ltration in partially molten rocks deformed in torsion with applications to melt extraction from Earth's mantle.(2010-10) King, Daniel S. H.Melt extraction from Earth's upper mantle requires transport of magma from regions of partial melting at depth to the Earth's surface. During its ascent, melt interacts chemically and mechanically with the rock matrix. Melt reduces the viscosity of the partially molten rock compared to that of a melt-free rock. This weakening is a potential mechanism of strain localization that could have significant geodynamical implications. Magma interacts chemically with mineral phases during its ascent, dissolving phases in which it is undersaturated and precipitating phases in which it is oversaturated. Such melt-rock reaction can be a driving force for melt migration. Water and other volatiles also partition into the melt from minerals and are then expelled to Earth's oceans or atmosphere. This process leaves behind stronger dehydrated rocks, and it could be the mechanism by which the oceanic lithosphere (mechanical boundary layer) is formed. The work presented here is an experimental investigation of several mechanisms that influence the distribution of melt within a viscously deformable partially molten rock. Three mechanisms are considered, either alone or in various combinations. (1) An applied shear stress causes melt to align and segregate into melt-rich bands with a consistent geometrical relationship to the shear geometry. In Chapter 2, we investigate possible means of scaling the bands that form in experimental samples to Earth's mantle and explore the evolution of melt-rich bands at high shear strain. (2) Interfacial tension driven flow acts to homogenize the distribution of melt within a partially molten sample. In Chapter 3, we investigate the evolution of melt distribution during static annealing of a sample containing melt-rich bands. We compare the experimental results with models of interfacial tension driven flow to determine which mechanisms control the rate of melt redistribution. (3) A melt source that is undersaturated in some component, when coupled with a sink that is rich in that component, will infiltrate into the sink through reactive flow. This reactive flow can develop into an instability in which fingers of high melt fraction propagate into the sink. In Chapter 4 we investigate this process both under static conditions and in combination with stress-driven melt segregation.