Oscillatory flows are frequently encountered in many micro/nanoelectromechanical systems, where the fluid can be either a liquid or a gas. For the former, the time-periodic fluid movement is coupled with electrokinetic effects arising from the electric double layer, while oscillatory gas flows may exhibit strong noncontinuum characteristics due to the small devise size and the high operating frequency. In this talk, a group of the lattice Boltzmann (LB) models are developed for capturing these distinct time-dependent flow features at the small scales. Importantly, the equations are formulated in the frequency domain, instead of the conventional time domain, to gain more concise LB algorithms. The results are validated against the available benchmarks and the LB simulations in different flow conditions are discussed. In particular, for oscillatory gas flows operating at high frequencies, a splitting method under the LB framework is proposed to achieve high numerical accuracy.

Lattice Boltzmann Method, Micro and Nanoscale, Oscillatory Flows