The flow behaviour and performance parameters of a diffuser-nozzle element of a valveless micropump have been investigated for different driving pressure frequencies. When a fluctuating pressure is imposed on the inlet boundary of a diffuser-nozzle element, there is a net flow in diffuser direction due to the dynamic effect. The variation of this net flow along with rectification capacity, and diffuser efficiency has been investigated for different frequencies of driving pressure. Flow behaviour and recirculation region due to dynamic effect have been studied as qualitative study. Pressure and velocity have been analyzed for quantitative analysis and for validation with results found in literature. 2-D geometry has been used in the present study. 3-D geometry has been modeled to justify the results obtained from 2-D analysis. Five different pressure frequencies ranging from 5 kHz to 50 kHz have been used to investigate their effects on the performance of diffuser-nozzle element in high frequency ranges. The net flow and performance of the nozzle-diffuser element are found to be decreasing with the increasing frequency. The performance is found to be less sensitive to frequency at high pressure range (above 30 kHz).
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