An efficient numerical method for predicting the performance of valveless micropump

Abstract

Numerical characterization of valveless micropumps involves fluid–structure interaction (FSI) between a membrane and the working fluid. FSI being computationally difficult, efforts have been mainly restricted to analyzing a given micropump performance. Designing an optimum micropump involves understanding the role of different geometric parameters and this forms the focus of the present work. It is shown that membrane displacement information extracted from a two-way coupled FSI simulation at a given frequency can be reliably used to carry out fluid flow simulations over a wide range of geometrical and operating parameters. The maximum variation between this approach and FSI is within 4% while there is a drastic reduction in computational time and resource. A micropump structure suitable for MEMS technology is considered in this work. An optimum micropump geometry, having a pump chamber height of 50 μm, diffuser length of 280 μm, throat width of 100 μm and separation distance between nozzle and diffuser openings of 2.5 mm, is recommended. The numerical prediction of flowrate at 200 Hz (68 μl min−1) for this pyramidal valveless micropump matches well with the experimental data (60 μl min−1) of the micropump fabricated using MEMS-based silicon micromachining. Thus an efficient numerical method to design valveless micropumps is proposed and validated through rigorous characterization.