Immersed Boundary-Lattice Boltzmann Study On Moving Mechanism Of Red Blood Cell In A Microvascular Bifurcation

Red blood cells are an important part of the blood.It is mainly responsible for the delivery of oxygen and nutrients to the organization.At the same time,RBCs take away the carbon dioxide produced.The main exchange site for these substances is the capillaries.The study of RBCs in the motor function and morphological changes in the law to reveal the relevant pathology has important significance.In recent years,there have been many methods for simulating red blood cells.In this paper,experimental and simulated control methods were used to study.In the experimental part,we use contrast microscope to observe the red blood cells of caudal fin.One of the bifurcated vessels was selected and an influx of cells was observed and analyzed.In the simulation part,the immersion boundary-lattice Boltzmann method(IB-LBM)was used to study the red blood cell movement in bifurcated capillaries.The interaction between cells and fluids was simulated using the immersion boundary method(IBM).The lattice Boltzmann method(LBM)was used to construct the flow field.The model was established by combining the experimental observations.First,we analyzed the changes of RBCs deformation and shear force in three different degrees of branch stenosis of single cell.And then,we change the boundary conditions of the channel which has the narrow part to observe the deformation of red blood cells.Subsequently,the similarity between the experiment and simulation is analyzed,and the feasibility of the model is further proved.To a certain extent,it can reflect the bifurcated blood vessels in the characteristics of red blood cells.Furthermore,we analyzed the movement mechanism of a group of cells in three different degrees of branch stenosis.The distribution of RBCs internal pressure in this model was studied in detail.We analyzed the effect of stenosis on the flow,shear force,red blood cell velocity,and the number of distributions of each channel.The following conclusions are obtained by simulation:(1)In the analysis of a group of cells,the degree of branch stenosis has an effect on the number of cells to be dispensed and the speed of movement.The increase of stenosis makes the distribution of cells in the narrow channel smaller.A decrease in the speed of a cell results in a greater pressure of the cell at the stenosis and a lower cell pressure at the bifurcation.As the speed of movement slows down,the shear rate becomes smaller.(2)For individual cell analyzes,the degree of branch stenosis has an effect on the velocity of the cells.The greater degree of stenosis,the longer time of cell passes through the stenosis.At the same time,cells through the narrow time accounted for the proportion of the entire movement cycle smaller.