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Laminar And Turbulent Flow Of A Liquid Through Channels With Superhydrophobic Walls Exhibiting Alternating Ribs And Cavities, Brady L. Woolford
Laminar And Turbulent Flow Of A Liquid Through Channels With Superhydrophobic Walls Exhibiting Alternating Ribs And Cavities, Brady L. Woolford
Theses and Dissertations
There is significant interest in reducing the frictional resistance that occurs along a surface in contact with a liquid. A novel approach to reducing the frictional resistance across a liquid-solid interface is the use of superhydrophobic surfaces. superhydrophobic surfaces are created in this work by the use of micro-fabrication techniques where systematic roughness is fabricated on a substrate surface which is subsequently treated with a hydrophobic coating. This work reports an experimental study of superhydrophobic surfaces used to reduce drag in both laminar and turbulent channel flows. In the laminar flow regime reductions in frictional resistance greater than 55% were …
Analysis Of Viscous Drag Reduction And Thermal Transport Effects For Microengineered Ultrahydrophobic Surfaces, Jason W. Davies
Analysis Of Viscous Drag Reduction And Thermal Transport Effects For Microengineered Ultrahydrophobic Surfaces, Jason W. Davies
Theses and Dissertations
One approach recently proposed for reducing the frictional resistance to liquid flow in microchannels is the patterning of micro-ribs and cavities on the channel walls. When treated with a hydrophobic coating, the liquid flowing in the microchannel wets only the top surfaces of the ribs, and does not penetrate into the cavities, provided the pressure is not too high. The net result is a reduction in the surface contact area between channel walls and the flowing liquid. For micro-ribs and cavities that are aligned normal to the channel axis (principal flow direction), these micropatterns form a repeating, periodic structure. This …
Microparticle Influenced Electroosmotic Flow, John M. Young
Microparticle Influenced Electroosmotic Flow, John M. Young
Theses and Dissertations
The influence of microparticles on electroosmotic flow was investigated experimentally and numerically. Experiments were conducted using four different particle types of varying chemical composition, surface charge and polarity. Each particle type was tested at five different volume fractions ranging from 0.001 – 0.025. With a constant applied electric field, positively charged particles enhanced the electroosmotic flow by as much as 850%. The enhancement depended on particle composition, size and concentration. For negatively charged particles, the bulk electroosmotic flow was retarded with the largest reductions being 35%. This occurred for the greatest negative paricle concentration studied. A final experimental study utilizing …