Analysis of slip flow in microchannels

Duan, Zhipeng (2007) Analysis of slip flow in microchannels. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Fluid flow in microchannels has emerged as an important research area. This has been motivated by their various applications in microfluidic systems, such as Micro-Electro-Mechanical Systems (MEMS). The advent of MEMS has opened up a new research area where non-continuum behavior is important. Microchannels are the fundamental part of microfluidic systems. Understanding the flow characteristics of microchannel flows is very important in determining friction factor, pressure distribution, heat transfer, and transport properties of the flow. The non-circular cross sections such as rectangular, triangular, and trapezoidal, are common channel shapes that may be produced through a variety of microfabrication techniques. These cross sections have extensive practical applications in MEMS. -- Developing and fully developed slip flow in non-circular microchannels has been investigated and models are proposed to predict the friction factor Reynolds product Æ’Re for slip flow in most non-circular microchannels. It is found that the linearization method to solve the Navier-Stokes equations is an accurate approximation for developing slip flows. -- Compressibility effects on slip flow in non-circular microchannels have been examined and simple models are proposed to predict the pressure distribution and mass flow rate for slip flow in most non-circular microchannels. -- The effects of corrugated surface roughness on fully developed laminar flow in microtubes are investigated. Novel analytical models are developed to predict friction factor and pressure drop in corrugated roughness microtubes for continuum flow and slip flow. The developed model for slip flow illustrates the coupled effects between velocity slip and corrugated roughness. -- Slip flow heat transfer in annular microchannels has been examined. The effects of Knudsen number, radii ratio and heat flux ratio on heat transfer characteristics are discussed. -- Analytical models have been developed to provide a means of predicting slip flow characteristics, such as friction factor, mass flow rate, and pressure distribution for fluids operating in microchannels. These models are general and robust, and can be used by the research community for practical engineering design of microchannel flow systems. This study may help understand the behavior of fluids in microchannels.

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