Fluid mixing by an electromagnetically driven floating rotor

Area of Science:

• Fluid Dynamics
• Electromagnetism
• Mixing Phenomena

Background:

• Electromagnetic stirring is crucial for fluid control in various applications.
• Understanding chaotic mixing in laminar flow regimes is essential for process optimization.
• Floating stirrers offer unique advantages in thin-layer fluid manipulation.

Purpose of the Study:

• To analyze the mixing properties of an electromagnetically driven floating stirrer in a thin electrolyte layer.
• To investigate the formation of coherent structures and their role in chaotic mixing.
• To determine optimal conditions for enhanced fluid mixing by manipulating rotor geometry.

Main Methods:

• Experimental characterization using dyed water visualization and particle image velocimetry (PIV).
• Quasi-two-dimensional numerical simulation employing the immersed boundary method.
• Analysis of fluid-solid interaction and flow dynamics at the electrolyte surface.

Main Results:

• Identification of a tripolar vortex structure with a central vortex synchronized with the rotor.
• Demonstration of chaotic mixing in the laminar regime (Reynolds number = 45).
• Experimental and numerical results show satisfactory agreement in characterizing mixing and flow dynamics.

Conclusions:

• The floating stirrer effectively induces chaotic mixing in thin electrolyte layers.
• Varying the distance between magnets in the rotor is key to optimizing mixing conditions.
• The study provides insights into controlling fluid interfaces for enhanced mixing processes.