Dean Flow Dynamics in Low-Aspect Ratio Spiral Microchannels.

Area of Science:

• Fluid dynamics
• Microfluidics
• Biophysics

Background:

• Microfluidic cell sorting relies on secondary flows in curvilinear channels.
• Existing models assume steady Dean vortices in rectangular spiral microchannels.
• Understanding flow dynamics is crucial for optimizing microfluidic device performance.

Purpose of the Study:

• To investigate secondary Dean flows in low aspect ratio spiral rectangular microchannels.
• To define the development of Dean flows concerning channel aspect ratio and Dean number.
• To explore the impact of multiple Dean vortices on particle and cell focusing.

Main Methods:

• Experimental and numerical investigation of Dean flows in microchannels.
• Analysis of flow behavior for Reynolds numbers (Re) > 100.
• Characterization of secondary Dean vortices beyond a critical Dean number.

Main Results:

• Demonstrated the presence of secondary Dean vortices beyond a critical Dean number in low aspect ratio spiral microchannels.
• Showcased the influence of these multiple vortices on particle and cell focusing.
• Provided new insights into secondary flow instabilities in microchannel geometries.

Conclusions:

• Secondary flow instabilities in low aspect ratio spiral microchannels are significant.
• Improved flow models can enhance the precision and efficiency of microfluidic devices.
• Findings are applicable to cell sorting, micromixing, and other microfluidic applications.