Hydrodynamic study of sperm swimming near a wall based on the immersed boundary-lattice Boltzmann method

This paper presents a numerical study on a sperm swimming in a viscous fluid by using an immersed boundary-lattice Boltzmann method (IB-LBM). The sperm is modeled simply by integrating a slender tail and an elliptical head. By applying a tail traveling wave vertical to the wall, a sperm swims near a surface is simulated. Based on which the corresponding swimming velocity, pressure, and shear stress are analyzed, and the mechanisms of accumulation and acceleration in the swimming process are further investigated. It is found when getting close to the wall, the integration of pressure gradient around the sperm increases, and then, the sperm is accelerated. On the other hand, we also observed that the integration of pressure gradient toward the wall tends to raise; this means a more considerable attraction from the wall occurs. These results provide us some new insights to understand the phenomena of the sperm's wall acceleration and wall accumulation. Moreover, the variations of the pressure and shear stress indices on the sperm suggested that some perceptible mechanical information based on the flow can be formed. Which reminded us that sperm might be able to sense the flow and adjust its motion.