Mixing Performance of a Passive Micromixer Based on Split-to-Circulate (STC) Flow Characteristics.

Area of Science:

• Fluid dynamics
• Microfluidics
• Chemical engineering

Background:

• Passive micromixers are crucial for efficient fluid manipulation in microfluidic devices.
• Achieving high mixing efficiency, especially at low flow rates, remains a significant challenge in microfluidics.

Purpose of the Study:

• To propose and analyze a novel passive micromixer design based on split-to-circulate (STC) flow characteristics.
• To comprehensively evaluate the mixing performance of the proposed micromixer across a broad range of Reynolds numbers.

Main Methods:

• Three distinct micromixer designs incorporating submerged circular walls were fabricated and tested.
• Computational fluid dynamics (CFD) simulations were used to analyze flow patterns and mixing efficiency.
• The degree of mixing (DOM) was quantified across a Reynolds number range of 0.1 to 80.

Main Results:

• The proposed micromixer consistently achieved a degree of mixing (DOM) exceeding 0.84 over the tested Reynolds number range (0.1–80).
• Significant mixing enhancement was observed in the low to intermediate Reynolds number range (0.1
• Key flow features, including saddle points and flow impingement, were identified as drivers of enhanced mixing.

Conclusions:

• The novel passive micromixer effectively leverages STC flow characteristics for superior mixing performance.
• The design demonstrates high mixing efficiency across a wide range of operating conditions, particularly at low Reynolds numbers.
• This micromixer represents a promising advancement for applications requiring efficient mixing in microfluidic systems.