Acoustic Radiation Pressure on a Solid Sphere in a Compliant Cylindrical Tube Filled with a Fluid

The problem of determining the acoustic radiation force acting on a rigid spherical particle is formulated. The particle is located in a thin flexible tube filled with a fluid. The problem is solved using the method of separation of variables, translational addition theorems for spherical wave functions, and expressions of spherical wave functions in terms of cylindrical wave functions and vice versa. The determination of the wave potential is reduced to the infinite system of algebraic equations obtained after satisfying the boundary conditions. The characteristics of the acoustic radiation force are studied depending on the primary wave frequency, the radius of the particle, the radius of the tube, the properties of the fluid, the wall thickness of the tube, and the elastic properties of the tube material. It is found that the behavior of the acoustic radiation force is non-monotonic. Both magnitude and direction of the force can vary significantly.