Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 31 for “"Pressure driven flow"”.
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A Numerical Study of the Flow and Heat Transfer in the Near Field of a Cylindrical Bubble Moving in a Narrow Channel
… is performed of a cylindrical bubble moving in a pressure-driven flow of Novec-649 in a heated channel. The upper wall is an electrically heated metal foil, and the bubble diameter is on the order of the channel spacing. Phase change is not included to isolate the contribution of the liquid motion …
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Investigation of a trapezoidal microchannel for hydrodynamic detachment of cells or biomolecules.
… This design utilizes the characteristic pressure-driven flow of microfluidics to detach cells or biomolecules at the narrow region of interest while enabling flexibility in the rest of the channel with larger height and low shear stress. A fluid dynamics analysis was performed …
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Gate potential control of nanofluidic devices
… concentration polarization effect, caused by pressure-driven flow in the nanofluidic channel, and showed that this phenomena can also be modulated by changing the gate potential of the nanofluidic devices. The gate potential effect opens the door for closed-loop real-time control of …
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Taylor-Aris dispersion in microfluidic networks
… examples, dispersion analysis of (non-reactive) pressure-driven flow in spatially periodic serpentine microchannels and reactive transport in an elementary geometric model of a porous medium; and (ii) a pair of case studies based upon the microfluidic separation techniques of vector …
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Dynamic simulations of particle suspensions subjected to an external electric-field
… studied both under static conditions and when a pressure driven flow is applied, and in the case of a uniform and non-uniform electric field. The results show that the electrostatic energy method applied in the past to the case of a uniform electric field only can be extended to the situation …
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Microfabricated magnetophoretic focusing systems for the separation of submicrometer particles
… developed: an Alternating Field System and a Flow System. Both systems consisted of permanent magnets and miniaturized devices (separation chips), which integrated microfluidic channels with ferromagnetic core elements. The systems produced "sawtooth" magnetic fields that were combined with a …
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Designing devices using electro-active yield stress fluids
… applications such as smart valves and semi-solid flow batteries. This thesis explores the rheological and electrical properties of EAYS fluids, with a focus on how the presence of a deformable microstructure, which gives rise to a yield stress at the macroscale, affects the design and performance …
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A Model for Determining Leakage in Water Distribution Systems
… consisting of continuity, energy (headloss), pressure-dependent demands and/or leakage, and flow direction preservation equations are utilized to distribute demand flows and leakage among pipes. The leakage is attributed to the formation of corrosion holes. Based upon the extent of corrosion, …
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Characterization of Pressure-Driven and Electro-Kinetically Driven Flow in a Micro-Fluidic Chip Using Particle Imaging Velocimetry
<p>The flow profiles of pressure-driven and electro-kinetic driven flows were compared for a microfluidic chip. It was found that the pressure-driven flow had a parabolic profile while the electro-kinetic flow had a plug shaped flow profile. The measured velocities were similar to those determined …
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Low-Cost Manufacturing of Electrokinetic Preconcentration Systems
… as a function of the applied voltage and the pressure-driven flow velocity. Finally, we explore alternate device designs made possible by our low-cost manufacturing methods and materials, to provide a guide for future improvements. Ultimately, our work demonstrates a novel fabrication method …
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Enhancing Micro Free Flow Electrophoresis: Detection, Application, And Fabrication
Micro Free Flow Electrophoresis (µFFE) is a separation technique where analytes are moved through a planar separation channel via pressure driven flow. Analytes streams are deflected laterally within an electric field applied perpendicular to the flow and separated from one another based on …
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Numerical and experimental investigation of composite heat pipe technology
… that pose very small thermal resistance to heat flow, even over relatively long transport paths. Utilizing two-phase heat transfer, they can transport heat from con fined spaces to remote heat sinks where more surface area might be readily available. This attribute is particularly useful in …
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Pressure and velocity fields in a relaxing three-dimensional turbulent boundary layer
Static pressure and mean velocity data were obtained in a relaxing shear driven three-dimensional incompressible turbulent boundary layer flow produced by a swept rectangular step. The nominally 10 cm (4 in.) thick boundary layer had a freestream velocity of approximately 25 m/sec (80 ft/sec). The …
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Pressure-driven and electroosmotically-driven liquid chromatographic separations in packed fused silica capillaries
… miniaturized liquid chromatographic system under pressure-driven flow is studied and the improved permeability of micropacked capillary columns is exploited in the manufacture of several 25 to 30cm columns which achieve high efficiencies with relatively low pressure drops. Van Deemter plots …
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Design and operation of microchemical systems for multistep chemical syntheses
… used to demonstrate 100% separation of two phase flows of hexane and water, toluene and water, dichloromethane and water, and hexane and methanol. Integrated liquid-liquid extraction devices are microfabricated that performed two -phase contacting by segmented flow, followed by separation - …
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Direct simulations of cells motions and deformations in flow
… of blood cells, especially leukocytes, in pressure driven flows in parallel plate channels with both smooth and uneven walls under adhesion force between the leukocytes and the channel wall. Leukocytes are represented by two composite fluid models. The first model is the compound-drop model …
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Polymer Microchips for Capillary Electrophoresis and Electric Field Gradient Focusing of Biomolecules
… These solvent-welded devices withstood internal pressures >2,200 psi, and 300 CE runs were performed on a single microchip without any loss of separation performance. Furthermore, CE separations of peptides and amino acids were completed in ~10 s, with peak efficiencies of 43,000 theoretical …
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Thermally Developing Electro-Osmotic Convection in Circular Microchannels
… developing, electro-osmotically generated flow has been analyzed for a circular microtube under imposed constant wall temperature (CWT) and constant wall heat flux (CHF) boundary conditions. Established by a voltage potential gradient along the length of the microtube, the hydrodynamics of …
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Vibrating lubricant-infused porous surface for enhanced liquid droplet transport
… Landau-Levich law — there is a zone of capillary pressure-driven flow inside the lubricant wetting ridge around the droplet base when the capillary number is much smaller than one. The viscous dissipative force, which resists this capillary suction of lubricant, depends non-linearly on the …
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A three-dimensional turbulent boundary layer upstream and around a junction vortex flow
A pressure-driven three-dimensional turbulent boundary layer flow upstream and around a junction vortex was experimentally studied and is offered for use as a benchmark flow for testing and evaluating the predictive ability of state-of-the-art three-dimensional turbulent boundary layer codes. The …
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