Numerical simulation and experimental measurement of fluid flow field in pipe with capsule robot

Capsule robots are widely used in the inspection and treatment of human intestines. According to the permanent magnet method, a magnetically controlled smooth capsule robot is designed and manufactured. Based on the Computational Fluid Dynamics (CFD) method, the fluid flow field (velocity and vorticity) around the capsule robot is numerically simulated when the capsule robot precesses (rotates and translates) in the pipe filled with mucus. The Particle Image Velocimetry (PIV) technology is used to measure the fluid flow field. The resistance, the resisting moment of the robot and the average turbulent intensity of the surrounding fluid are further calculated as the capsule robot precesses at different rotational speeds. Finally, the shape and distribution of fluid streamlines, and the distribution and size of the fluid velocity and vorticity around the capsule robot are also experimentally measured. The results show that: 1) when the rotational speed of the capsule robot is increased, the fluid velocity and vorticity in the surrounding and lower regions of the capsule robot are slightly increased, while the fluid streamlines and vorticity distribution of the surrounding fluid are basically similar. 2) With the increase of the rotational speed of the capsule robot, the resisting moment of the capsule robot in the forward direction and the average turbulent intensity of the surrounding fluid are all increased, while the resistance of the capsule robot in the forward direction remains basically unchanged. 3) The experimentally measured shape and distribution of fluid streamlines, and the measured distribution and size of the fluid velocity and fluid vorticity around the capsule robot are basically similar to the numerical calculation results.