Numerical and Experimental Investigation of Thermocapillary Pumping in Closed-end Microchannels for Micro Heat Engines
Library & Archives Canada, 2008 - 159 pages
The numerical formulation uses a new adaptive grid formulation with a sliding staggered grid in the micro-droplet, all expanding/contracting grid in the compressed gas section and an adaptive grid in the substrate section of the microchannel. Unlike past studies with a Poiseuille velocity profile, this thesis simulates re-circulation in the corners of the micro-droplet. These predictions entail fully coupled pressure/velocity fields at the droplet/air interface. Furthermore, in contrast to past studies with a uniform interfacial pressure, the numerical model accommodates a varying interfacial pressure along the receding edge of the micro-droplet. Temperature boundary conditions for a stationary heat source are applied at the interface between the substrate and its surroundings, rather than along the microchannel wall. The fluid momentum equations are solved with a staggered grid and adaptive mesh refinement at the liquid/gas interfaces. This refinement uses Bernstein polynomials and control points to adjust the grid spacing. Heat transfer across a thermal bridge within the substrate generates cyclic heating and cooling periods during the micro-droplet transport.
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