Numerical Studies On The Motion,Deformation And Aggregation Of Red Blood Cells In Bifurcated Microvessels

In all blood cells,red blood cells account for 99%,red blood cells account for about 45%of all blood cells in number,so that they determine properties of the whole blood to some extent,therefore,it is very important to study the motion and deformation of red blood cells in the microcirculation.On the one hand,the microcirculation system is not only the basis for sustaining life activities,but also the transportation of matter and energy in the human body,and the microcirculation is closely related to the normal function of tissues and organs.On the other hand,due to red blood cells have a significant influence in the microcirculation,if the red blood cells are abnormal in morphology or mechanical properties,it will lead to the occurrence of diseases such as malaria.In this dissertation,we studied the three-dimensional motion,deformation and aggregation of red blood cells in bifurcated microvessels,we used a coupled method of smooth dissipative particle dynamics(SDPD)and immersed boundary method(IBM).Smoothing dissipative particle dynamics is used to simulate the motion of the internal and external fluids of red blood cells,and the interaction between red blood cells and fluids is treated by immersed boundary method.The red blood cell membrane was constructed as a triangular grid,and the red blood cell membrane not only resists stretching and bending deformation,but also keeps the volume and surface area of red blood cells almost unchanged.First,we studied the motion and deformation of a single red blood cell in the bi-furcated microvessels.During the numerical simulation,we found that when red blood cells flow through the bifurcated microvessels,the red blood cell deformation was divid-ed into five stages.In these five stages,red blood cells have similar deformation trends,but have different deformation indexes,it was affected by different bifurcation configu-rations and different red blood cell characteristics.Secondly,we studied the effects of the number,mechanical properties and interaction intensity of red blood cells on the motion,deformation and aggregation of red blood cells.During the simulation,it was observed that multiple red blood cells at the bifurcation showed a similar deformation to a single red blood eell,and also had five deformation stages.It was also found that the motion,deformation and aggregation of red blood cells were mixed and interacted.The deformation of red blood cells had a significant influence on the aggregation of red blood cells,and the aggregation of red blood cells had a slight influence on the deformation of red blood cells.The deformation and aggregation of red blood cells can cause the center of mass of the red blood cells to deviate at the apex of the bifurcation,causing the red blood cells to slide into different branches.Finally,we studied the distribution of a large number of red blood cells in the microvascular network,includ-ing the deformability,aggregation and hematocrit of red blood cells.We found that the lower the deformability of red blood cells,the stronger aggregation or the higher hematocrit,the separation of blood cells and plasma in the microcirculation.These studies help to understand the motion,deformation and aggregation behavior of red blood cells in the microcirculation.