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SUMMARYGas ow in micro-electro-mechanical systems can be considered as rareÿed since the ratio of free molecular path length to the characteristic length of the device is high. It is possible to analyse these ows using a conventional Navier-Stokes solver with modiÿed boundary conditions to account for temperature-jump and slip-velocity on solid walls. In this study, characteristic-based-split (CBS) algorithm is modiÿed to account for slip-velocity and temperature-jump boundary conditions in order to perform compressible ow analysis for a micro sized geometry. The CBS algorithm is a split procedure which yields a uniÿed solution method valid for both compressible and incompressible ows. To verify the modiÿed CBS solver, straight micro channel and micro step duct geometries are selected as test cases. To reduce the size of the implicit part of the algorithm, pseudo-quadratic velocity=linear pressure elements (pP2P1) are employed. The results obtained using CBS algorithm, are compared with other analytical and computational results available in the literature. It is shown that this implementation of the CBS algorithm is applicable and e ective for micro gas ows. It is also shown that, increasing Knudsen number results in increased temperature-jump and slip-velocity. This e ect, however, is limited, especially for high Mach number ows.

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Flow field generated in and around micro synthetic jet actuator is analyzed using the an existing Navier-Stokes solver.The solver is modified to accomodate slip wall boundary condition proposed in literature for micro scale flow problems. Two actuator cavity shapes, rectangular and triangular, are investigated for quiscent and cross-flow external domain conditions.

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