Session: 04-01 Numerical and Data Based Methods for Multiphase Flows

Paper Number: 87470

87470 - A Study of Microfluidic Device Geometries on Fluid Instabilities 

Computational fluid dynamics (CFD) analysis is applied to increase the understanding of gravity on fluid instability phenomenon. The effort specifically studies viscous fingering patterns in a microfluidic device to support microgravity experiments that will utilize imagery using a lens free imaging (LFI) system to capture the data. The purpose of the study is to provide valid preliminary data using STAR-CCM+, a CFD analysis software, to predict the viscous behavior in an upcoming suborbital flight experiment using microfluidic flow. A plethora of CFD models were created to determine predicted Saffman-Taylor or viscous fingering instability in microfluidic devices using liquids with ranging viscosities; the microfluidic devices were pre-filled with corn syrup (high viscosity) and then injected with ethanol (low viscosity). This was simulated at various orientations to study the effect gravity has on the viscous patterns of the incoming low viscous flow and using numerous device geometries with varying inlet angles. Lab experiments were then conducted to validate the computational models. A study was done to quantify the viscous finger length and width with respect to different microfluidic device geometries. The results show a correlation between viscous finger patterns and the device geometry. This study shows how the changing device geometries impacts viscous finger patterns. The data captured in the lab showed that a few parameters were dominant in the changing behavior, such as channel height of the device and inlet nozzle angles. Focusing on these parameters and comparing them to the CFD results provide further insight into the accuracy of the CFD modeling with respect to microfluidics behavior. Understanding fluid instabilities provides researchers with a better understanding of the onset of turbulence. This is an important concept for many engineering applications, from aircrafts to ocean currents to biofluids. The work done in this experiment is to test microfluid instabilities under ideal conditions. The CFD approach allows for testing of various parameters, such as device geometry, flow rate, viscosity or density ratios, and inlet nozzle angles. The work in this experiment provides a guideline to generate fluid instabilities using these parameters.

The expected result of this experiment is that device geometries have a large impact on fluid instabilities in the microfluidic domain and the chosen CFD software can reflect this change well. As the experimental parameters (geometry, channel height) change, CFD will be able to accurately predict the behavior of the low viscous fluid flow. The final paper will document the methods used to execute the experiments in the lab, along with the results in a clear and concise manner. It will compare the lab outcome with varying device geometries and gravity orientations with the generated CFD results. Finally, it will discuss the accuracy of the CFD software followed by the conclusion.

Presenting Author: Taylor Peterson University of Central Florida