Viscous losses in porous media and jet-pumps under oscillatory flow conditions

The first part of the dissertation addresses the direct measurement of the complex density function characterizing the viscous coupling of the gas to the walls in a porous material. After discussing the experimental technique, results are shown for single circular pores, two pin-array geometries and two porous materials. The data obtained for the single pores and the pore array agrees very well to theoretical predictions. For the porous samples and the transverse pin-array, the different length scales corresponding to thermal and viscous couplings are evident when plotting the corresponding measured functions together. The second part deals with oscillatory flow rectification and minor-losses in jet-pumps at high amplitudes where a time-averaged pressure component appears across the sample. Minor-loss coefficients are calculated from the high-amplitude resistance and time-averaged pressure curves for a range of edge curvatures and opening angles. The corresponding steady-flow coefficients are also measured using a simple setup. Good agreement is found between the steady and oscillatory flow measurements, verifying the so-called Iguchi hypothesis.