The Morphological Analysis And Simulation Of The Motion Of Red Blood Cells In Capillaries

It is very important to research the motion of red blood cells in microcirculation. On the one hand the circulatory system is responsible for the transport of matter and energy in the human body, which is the basis of life-sustaining activities. And the microcirculatory system is associated with the normal function of tissues and organs. On the other hand many diseases will have influence on the microcirculatory system, which may be caused by microcirculation disorder. So the microcirculation detection can be used as an important basis of diagnosis. Therefore, the analysis of the motion and deformation mechanics of red blood cells in capillaries is very useful, and it provides valuable information on human body.There are three kinds of methods in microcirculation research field, the theoretical model method, experimental method and numerical analysis method. Researchers mainly adopt the theoretical model method in the early flow research. Along with the progress of the experimental method, the experimental observation method has greatly expanded the people’s perception of fluid phenomenon. But, the phenomenon of fluid is complex and changeable, the research methods needs to be improved. The progress of computational fluid dynamics makes numerical simulation implemented. Now, it has become the mainstream research methods, which is also used in this paper. The digital simulation can simulate a variety of practical problems, but the differences of different algorithms for the different problems are very big. Considering the characteristics of microcirculation fluid mechanics, this paper adopted the ALE method and Level set method. When red blood cells through tiny capillaries it’s shape change largely, it is very important in the numerical simulation, which influences the accuracy of the simulation results directly. ALE method has obvious advantages in dealing with such problems in the grid deformation process and has been widely used in other areas. Level set method is introduced to deal with the moving boundary problem, it can track the moving interface, has powerful topology description and implement easily. Digital simulation methods need to establish the model of the research object. In this paper, the blood vessel model describes the size and shape of blood vessels; flow field model describe the state of flow field in the blood vessels; RBC model describe the shape of red blood cells and film properties. Then the computing grid is divided, set the appropriate properties and conditions, and finally solve the equation by computer. The environment of microcirculation hydrodynamic is complex, there are many factors influence the result. The paper analyzes the deformation of red blood cells in various capillary number, and capillary number and the viscosity ratio affects the lateral migration of red blood cell. The results show that when the capillary number increases the deformation is more and more tend to X axis alignment. The cell migration movement decreases with the approach of cells to the center line of the catheter. When the capillary number is larger, the shape of the cells present asymmetric; the cell deformation changes greatly only during the initial transient and then into a quasi steady state; migration velocity, deformation degree decrease with the increasing of viscosity ratio.