Numerical investigation of ultrasonically driven multi-particle transport in microchannels using a strongly coupled...

To investigate the transport behavior of multiple particles in microchannels under ultrasonic actuation, a strongly coupled PD-IB-CLBM framework is developed in this work. In this framework, peridynamics (PD) is employed to describe the motion and deformation of solid particles, the cascaded lattice Boltzmann method (CLBM) is used to resolve the flow field, and the immersed boundary method (IBM) is adopted to enforce fluid-solid coupling. Based on this model, the migration dynamics of single and multiple particles in single-channel, parallel multi-channel, and T-shaped microchannels are systematically studied, with emphasis on the effects of particle number, channel geometry, and ultrasonic frequency on inlet capture, stable transport, and path selection. The results show that particle transport generally undergoes a transition from an initial oscillatory stage to a stable directional transport stage. Increasing particle number intensified inlet competition and trajectory disorder, potentially hindering the smooth entry of some particles. Parallel multi-channel structures enhance the capacity for simultaneous particle transport, but also introduce more pronounced local flow disturbances. In T-shaped channels, the transport behavior is highly sensitive to ultrasonic frequency. Among the tested conditions, 2 MHz achieves the best balance among capture range, flow stability, and transport consistency, whereas excessively high frequency (5 MHz) leads to an overly narrow effective capture region and deteriorates stable multi-particle transport. These findings reveal the coupled regulatory effects of ultrasonic frequency and channel geometry on collective particle transport, and provide theoretical guidance for ultrasound-assisted microfluidic manipulation and transdermal drug delivery systems.