Particle transport in tubes by Bessel-beam acoustic radiation force.

In confined fluidic environments such as biological vessels and microfluidic tubes, the behavior of acoustic radiation forces (ARFs) remains insufficiently understood, as most existing studies rely on plane-wave excitation and simplified lossless assumptions, leaving the effects of complex fields - particularly Bessel beams - in viscous, confined geometries largely unexplored. This paper develops a comprehensive theoretical framework for calculating the ARF exerted on a spherical particle suspended in a viscous fluid inside a cylindrical tube under Bessel-beam excitation. An analytical solution is derived, explicitly incorporating the influences of particle size, tube radius, and fluid viscosity. To validate the model, extensive numerical calculations and finite element simulations are performed, supplemented by experimental measurements. The results from theory, numerical modeling, and experiments consistently show excellent agreement across a wide range of particle radii, tube dimensions, and fluid viscosities, confirming the robustness of the proposed analytical model and providing a reliable tool for predicting particle conveyance in viscous, confined tubular environments driven by acoustic fields.