Fluid flow within microchannels plays a pivotal role in optimizing the performance of high-density electronic cooling systems, advancing microreactor technologies, and elevating the efficiency of microfluidic devices. Traditional fixed approaches, however, incur high costs and exhibit limited adaptability to dynamic operational conditions. A primary obstacle in achieving superior heat transfer in microchannels lies in facilitating effective fluid mixing and transport. This investigation employs numerical simulations to examine the oscillatory dynamics of magnetic micropillars in a microchannel subjected to concurrent magnetic field and fluid influences. A composite material comprising polydimethylsiloxane (PDMS) and magnetic nanoparticles was modeled to represent magnetic coupling effects. The analysis elucidates the micropillars' behavior under magnetic field modulation, revealing key interactions between magnetic forces and fluid dynamics. Results demonstrate that magnetic field application amplifies the micropillars' bending angle from 28° to 70°, with a maximum von Mises stress at the base approximating 1.2 MPa, signifying robust magnetic responsiveness. In the fluid-solid coupled microchannel, the magnetic field induces a marginal 0.7% reduction in peak mainstream velocity, while elevating peak vorticity ω_z from 2.1 × 10^-1 to 4.0 × 10^-1, thereby markedly enhancing mixing efficiency. These findings establish a theoretical framework for leveraging magnetic micropillars to augment heat and mass transfer processes.
 

Magnetically actuated flexible micropillar, Microfluidic mixing enhancement, Enhanced heat transfer