Historically exceptional observations of the blood movement in capillary vessels were revealed by Poiseuille. He found that blood corpuscles in flowing serum undergo only axial movement near the center of the vessels, whereas they rotate near the wall and in the intermediary space. This behavior generated the lift force. Poiseuille’s study of the effect of temperature gradient on the motion of the blood corpuscles resulted in the discovery of thermal diffusion. Recent investigation of the origin of the lift forces, applied on the ring-shaped two-dimensional particles, indicated an important difference between the theoretical and the experimental results and disclosed the necessity to take into account the three-dimensional sphere instead of the ring. The model of creeping flow of the liquid around the spherical particle is proposed to calculate the mean impact forces per unit area induced by the liquid streams in collisions with the surfaces of the upper and lower hemispheres of the particle. The difference of these forces between two hemispheres gives rise to the rotation of the particle and to the consequent lift force. This theoretical model approaches significantly the experimental data, but slightly deviates from them within the whole range of liquid flow velocities. The disaccord is due to the particle’s surface nature which is not smooth. The imperfections of the surface influence the effective particle size because the layer thickness of the species adhering to the surface can depend on the liquid flow velocity. Newton’s iteration method was used to obtain the correction factors. Then the first theoretical data calculation approach was corrected to obtain the second approach which fits almost perfectly the experimental data.
Josef Janča (Mon,) studied this question.