Session: 09-03: Computational Methods in Micro/ Nanoscale Transport

Paper Number: 131887

131887 - Effect of Adjacent Synthetic Jets on Mass Transfer in Microchannels 

Abstract: 

A numerical study is performed to investigate the effect of a pair of adjacent synthetic jets on fluid dynamics inside a microchannel. Subsequently, optimal conditions are considered to present the influence of micro synthetic jets on enhancing mass transfer at the micro scale. A synthetic jet is produced by the oscillatory movement of a membrane inside a cavity, causing fluid to enter and leave through a small orifice. Ejection and ingestion of fluid from or into an orifice causes the formation of a counter-rotating vortex pair with each cycle. The vortex can persist and propagate during the suction stage, which develops into a train of vortices, and a jet is formed. Synthetic jets are interesting because of their unique characteristics being zero net mass flux. Besides, their compatibility, low cost, and no need for supplemental equipment such as piping, pump, etc. makes them attractive for use at the microscale. In the case of adjacent synthetic jets, vortices ejected from adjacent orifices interact with each other depending on the operation conditions. This structure gives an opportunity to control the direction and strength of the jet based on mass transfer or pumping requirements. Fluid flow inside microchannels is typically laminar due to their small scale. In this condition, mixing and mass transfer depend on natural diffusion, resulting in prolonged durations and lower mixing quality per unit length, which is unsuitable for engineering or biomedical applications.This also holds true for circumstances where disturbing the thermal boundary layer is necessary. In this study, a robust numerical method is conducted by considering diaphragm motion using Ansys Fluent to show the effect of using adjacent micro synthetic jets in different operating conditions on mass transfer at the microscale. In the case of synthetic jets, a numerical study has can obtain much more flow field details in comparison with an experimental study due to the inherent characteristics of synthetic jets . These conditions become more challenging when it comes to microscale. At first, the impact of difference in the operating phase of diaphragms (0 ≤ φ ≤ 180) on the structure of vortices generated by adjacent synthetic jets is considered. Then, the morphology of fluid flow inside micro channels is presented. The behaviour of adjacent synthetic jets in the presence of the cross flow is investigated. Merging, tilting, and vectoring of the vortices and their effect on flow inside the microchannel are discussed. The results of this study showed that the presented method can effectively increase mass transfer at micro scale under controlled conditions.

Presenting Author: Delara Soltani TUDublin

Presenting Author Biography: She is a PhD student at TUDublin where her research focuses on micro synthetic jets and their application in enhanced mixing at the micro scale. she received her MSc from the University of Tehran. Her project focused numerical study of the behavior of a round liquid jet under forced perturbation with the low-velocity coaxial gas flow. She published her results in high-quality peer-reviewed journals. She is interested in using and developing CFD methods to enhance understanding of the fluid mechanics of liquid jets.

Authors:

Delara Soltani TUDublin
Tim Persoons Trinity College Dublin
Sajad Alimohammadi TUDublin