Browsing by Author "Wright, Ian"
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Item Fundamental tradeoffs generating the worldwide leaf economics spectrum(Ecological Society of America, 2006) Shipley, Bill; Lechowicz, Martin J; Wright, Ian; Reich, Peter BRecent work has identified a worldwide “economic” spectrum of correlated leaf traits that affects global patterns of nutrient cycling and primary productivity and that is used to calibrate vegetation–climate models. The correlation patterns are displayed by species from the arctic to the tropics and are largely independent of growth form or phylogeny. This generality suggests that unidentified fundamental constraints control the return of photosynthates on investments of nutrients and dry mass in leaves. Using novel graph theoretic methods and structural equation modeling, we show that the relationships among these variables can best be explained by assuming (1) a necessary trade-off between allocation to structural tissues versus liquid phase processes and (2) an evolutionary trade-off between leaf photosynthetic rates, construction costs, and leaf longevity.Item Velocity Measurements and Flow Visualization in Low Viscosity Jets(2020-08) Wright, IanMixing of a liquid jet into a surrounding fluid is a commonly encountered phenomenon in both natural and engineering systems. Understanding the influence of viscosity ratio on jet stability can help design fluid systems with enhanced or suppressed mixing characteristics. Experiments were conducted with low viscosity axisymmetric liquid jets to characterize the behavior of instabilities as a function of viscosity ratio. In the experiment, viscosity ratios M (ambient-to-jet) from 1 to 50 were imaged in a constant density environment at jet Reynolds numbers ranging from 794 to 2464. Images display a change from axisymmetric jet breakup to a helical mode at high Reynolds numbers and high ambient-to-jet viscosity ratios. Additionally, hot film velocity measurements were taken to characterize the jet profile and quantitatively measure both the mean and fluctuating velocity fields. The spectral data captured singular peaks in the frequency domain, in the range of 6-30 Hz. This peak frequency was further shown to have a dependence on both the jet Reynolds number and the ambient-to-jet viscosity ratio. Images of jet breakup, jet velocity profiles, and velocity instability spectra are shown and discussed.