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Full-Text Articles in Engineering

Drag Reduction In Turbulent Flows Over Micropatterned Superhydrophobic Surfaces, Robert J. Daniello Jan 2009

Drag Reduction In Turbulent Flows Over Micropatterned Superhydrophobic Surfaces, Robert J. Daniello

Masters Theses 1911 - February 2014

Periodic, micropatterned superhydrophobic surfaces, previously noted for their ability to provide drag reduction in the laminar flow regime, have been demonstrated capable of reducing drag in the turbulent flow regime as well. Superhydrophobic surfaces contain micro or nanoscale hydrophobic features which can support a shear-free air-water interface between peaks in the surface topology. Particle image velocimetry and pressure drop measurements were used to observe significant slip velocities, shear stress, and pressure drop reductions corresponding to skin friction drag reductions approaching 50%. At a given Reynolds number, drag reduction was found to increase with increasing feature size and spacing, as in …


Analytical Modeling Of Tree Vibration Generated During Cutting Process, Payman Karvanirabori Jan 2009

Analytical Modeling Of Tree Vibration Generated During Cutting Process, Payman Karvanirabori

Masters Theses 1911 - February 2014

There are several ways to cut down a tree. The piece by piece cutting method is studied in this research. By modeling the cutting process into simple dynamic models and obtaining governing equations of motion of tree and cut piece in each model, the forces during cutting process were calculated. The method was then applied to a set of real data and tree vibrations were compared with field measurements. The study is very rare in the case of the variety of the topics it covers from dynamics and mechanics to finite element modeling of a biological system.