Modeling of contactless bubble–bubble interactions in microchannels with integrated inertial pumps

Abstract

In this study, the non-linear effect of contactless bubble-bubble interactions in inertial micro-pumps is characterized via reduced parameter one-dimensional and three-dimensional computational fluid dynamics (3D CFD) modeling. A one-dimensional pump model is developed to account for contactless bubble-bubble interactions, and the accuracy of the developed one-dimensional model is assessed via commercial volume of fluid CFD software, FLOW-3D. The FLOW-3D CFD model is validated against experimental bubble dynamics images as well as experimental pump data. Pre-collapse and post-collapse bubble and flow dynamics for two resistors in a channel have been successfully explained by the modified one-dimensional model. The net pumping effect design space is characterized as a function of resistor placement and firing time delay. The one-dimensional model accurately predicts cumulative flow for simultaneous resistor firing with inner-channel resistor placements (0.2L < x < 0.8L where L is the channel length) as well as delayed resistor firing with inner-channel resistor placements when the time delay is greater than the time required for the vapor bubble to fill the channel cross-section. In general, one-dimensional model accuracy suffers at near-reservoir resistor placements and short time delays which we propose is a result of 3D bubble-reservoir interactions and transverse bubble growth interactions respectively that are not captured by the one-dimensional model. We find that the one- dimensional model accuracy improves for smaller channel heights. We envision the developed one-dimensional model as a first-order rapid design tool for inertial pump based microfluidic systems operating in the contactless bubble-bubble interaction non-linear regime.

BibTeX

@article{hayes2021modeling,
  year = {2021},
  publisher = {American Institute of Physics},
  author = {Hayes, B. and Whiting, G. L. and MacCurdy, R.},
  title = {Modeling of contactless bubble–bubble interactions in microchannels with integrated inertial pumps},
  journal = {Physics of Fluids},
  volume = {33},
  number = {4},
  pages = {042002},
  doi = {10.1063/5.0041924},
  url = { https://doi.org/10.1063/5.0041924},
  eprint = { https://doi.org/10.1063/5.0041924},
}