Numerical simulations are performed to examine the packing behavior of human red blood cells(RBCs). A combined ?nite-discrete element method(FDEM) is utilized, in which the RBCs are modeled as no-friction and no-adhes...Numerical simulations are performed to examine the packing behavior of human red blood cells(RBCs). A combined ?nite-discrete element method(FDEM) is utilized, in which the RBCs are modeled as no-friction and no-adhesion solid bodies. The packed volume and the void ratio of a large number of randomly packed RBCs are clari?ed,and the effects of the RBC shape, the mesh size, the cell number, and the container size are investigated. The results show that the packed human RBCs with normal shape have a void ratio of 28.45%, which is slightly higher than that of the ?at or thick cells used in this study. Such information is bene?cial to the further understanding on the geometric features of human RBCs and the research on RBC simulations.展开更多
This paper aims at providing a scientific basis for unifying the normal reference value standards of red blood cell count of Chinese presenile men. The paper, using microscopical counting method, studies the relations...This paper aims at providing a scientific basis for unifying the normal reference value standards of red blood cell count of Chinese presenile men. The paper, using microscopical counting method, studies the relationship between the normal reference values of 38,061 samples of red blood cell count of presenile men and eight geographical factors in 297 units in China. It is found that the correlation of geographical factors and the normal reference value of red blood cell count of presenile men is quite significant （F=303.00, P=-0.000）. By using the method of stepwise regression analysis, one regression equation is inferred. It is concluded that if geographical data are obtained in a certain area, the normal reference value of red blood cell count of presenile men in this area can be reckoned by using the regression analysis. Furthermore, according to the geographical factors, China can be divided into eight regions： Northeast China Region, North China Region, Shanxi-Shaanxi-Irmer Mongolia Region, Middle and Lower Reaches of the Changjiang River Region, Southeast China Region, Northwest China Region, Southwest China Region and Qinghai-Tibet Plateau Region.展开更多
A lattice Boltzmann model is presented to simulate the deformation and motions of a red blood cell （RBC） in a shear flow. The curvatures of the membrane of a static RBC with different chemical potentiM drops calcula...A lattice Boltzmann model is presented to simulate the deformation and motions of a red blood cell （RBC） in a shear flow. The curvatures of the membrane of a static RBC with different chemical potentiM drops calculated by our model agree with those computed by a shooting method very well. Our simulation results show that in a shear flow, biconcave RBC becomes highly flattened and undergoes tank-treading motion. With intrinsically parallel dynamics, this lattice Boltzmann method is expected to find wide applications to both single and multi-vesicles suspension as well as complex open membranes in various fluid flows for a wide range of Reynolds numbers.展开更多
This paper studies red blood cell （RBC） partitioning and blood flux redistribution in microvascular bifurcation by immersed boundary and lattice Boltzmann method. The effects of the initial position of RBC at low Re...This paper studies red blood cell （RBC） partitioning and blood flux redistribution in microvascular bifurcation by immersed boundary and lattice Boltzmann method. The effects of the initial position of RBC at low Reynolds number regime on the RBC deformation, RBC partitioning, blood flux redistribution and pressure distribution are discussed in detail. It is shown that the blood flux in the daughter branches and the initial position of RBC are important for RBC partitioning. RBC tends to enter the higher-flux-rate branch if the initial position of RBC is near the center of the mother vessel. The RBC may enter the lower-flux-rate branch if it is located near the wall of mother vessel on the lower-flux-rate branch side. Moreover, the blood flux is redistributed when an RBC presents in the daughter branch. Such redistribution is caused by the pressure distribution and reduces the superiority of RBC entering the same branch. The results obtained in the present work may provide a physical insight into the understanding of RBC partitioning and blood flux redistribution in microvascular bifurcation.展开更多
Experimental observations show that a strong magnetic field has a dramatic influence on the sedimentation of RBCs,which motivates us to model the sedimentation of red blood cell(RBC)under strong external magnetic body...Experimental observations show that a strong magnetic field has a dramatic influence on the sedimentation of RBCs,which motivates us to model the sedimentation of red blood cell(RBC)under strong external magnetic body force.To model the sedimentation of a RBC in a square duct and a circular pipe,a recently developed technique derived from the lattice Boltzmann and the distributed Lagrange multiplier/fictitious domain methods(LBM-DLM/FD)is extended to employ the mesoscopic network model for simulations of the sedimentation of a RBC in flow.The flow is simulated by the LBM with a strong magnetic body force,while the network model is used for modeling RBC deformation.The fluid-RBC interactions are enforced by the Lagrange multiplier.The sedimentation of RBC in a square duct and a circular pipe is simulated,which demonstrates the developed method’s capability to model the sedimentation of RBCs in various flows.Numerical results illustrate that the terminal settling velocity increases incrementally with the exerted body force.The deformation of RBC has a significant effect on the terminal settling velocity due to the change in the frontal area.The larger the exerted force,the smaller the frontal area and the larger the RBC deformation become.Additionally,the wall effect on the motion and deformation of RBC is also investigated.展开更多
In this article, a computational model and related methodologies have been tested for simulating the motion of a malaria infected red blood cell （iRBC for short） in Poiseuille flow at low Reynolds numbers. Besides t...In this article, a computational model and related methodologies have been tested for simulating the motion of a malaria infected red blood cell （iRBC for short） in Poiseuille flow at low Reynolds numbers. Besides the deformability of the red blood cell membrane, the migration of a neutrally buoyant particle （used to model the malaria parasite inside the membrane） is another factor to determine the iRBC motion. Typically an iRBC oscillates in a Poiseuille flow due to the competition between these two factors. The interaction of an iRBC and several RBCs in a narrow channel shows that, at lower flow speed, the iRBC can be easily pushed toward the wall and stay there to block the channel. But, at higher flow speed, RBCs and iRBC stay in the central region of the channel since their migrations axe dominated by the motion of the RBC membrane.展开更多
One of the important features of the microvessels is with permeable vessels.The hyperpermeablility is especially prounounced due to the fast grow of the microvessel in the tumor tissues.Flow field induced by leakage o...One of the important features of the microvessels is with permeable vessels.The hyperpermeablility is especially prounounced due to the fast grow of the microvessel in the tumor tissues.Flow field induced by leakage often presents a different figure compared to that of the health vessel.Non-uniform velocity and pressure distribution are found in the simulation by using Lattice Boltzmann Method combined with Starling law.This non-uniform flow field has significant influence on the mass transport in permeable mocrovessel,such as the motion of red blood cell.Using 2D spring network model to express the red blood cell and immersed boundary method to implement the coupling of fluid and structure,numerical simulations were carried out to study the migration of a red blood cell in a straight permeable channel.The results show that the staying time of red blood cell in the leakage region increases with the intensity of leakage.We also found that the leakage can weaken the lateral migration of the red blood cell from the wall to the channel center,and even tune the migration towards the wall when the leakage is reasonably strong.展开更多
基金Project supported by the Engineering and Physical Sciences Research Council(EPSRC)Turbulence Consortium Grant(No.EP/G069581/1)the Marie Curie International Incoming Fellowship(No.PIIF-GA-253453)
文摘Numerical simulations are performed to examine the packing behavior of human red blood cells(RBCs). A combined ?nite-discrete element method(FDEM) is utilized, in which the RBCs are modeled as no-friction and no-adhesion solid bodies. The packed volume and the void ratio of a large number of randomly packed RBCs are clari?ed,and the effects of the RBC shape, the mesh size, the cell number, and the container size are investigated. The results show that the packed human RBCs with normal shape have a void ratio of 28.45%, which is slightly higher than that of the ?at or thick cells used in this study. Such information is bene?cial to the further understanding on the geometric features of human RBCs and the research on RBC simulations.
基金Under the auspices of the National Natural Science Foundation of China (No. 40371004)
文摘This paper aims at providing a scientific basis for unifying the normal reference value standards of red blood cell count of Chinese presenile men. The paper, using microscopical counting method, studies the relationship between the normal reference values of 38,061 samples of red blood cell count of presenile men and eight geographical factors in 297 units in China. It is found that the correlation of geographical factors and the normal reference value of red blood cell count of presenile men is quite significant （F=303.00, P=-0.000）. By using the method of stepwise regression analysis, one regression equation is inferred. It is concluded that if geographical data are obtained in a certain area, the normal reference value of red blood cell count of presenile men in this area can be reckoned by using the regression analysis. Furthermore, according to the geographical factors, China can be divided into eight regions： Northeast China Region, North China Region, Shanxi-Shaanxi-Irmer Mongolia Region, Middle and Lower Reaches of the Changjiang River Region, Southeast China Region, Northwest China Region, Southwest China Region and Qinghai-Tibet Plateau Region.
基金supported by National Natural Science Foundation of China under Grant No. 10747004the Guangxi Science Foundation under Grant Nos. 0640064 and 0542045
文摘A lattice Boltzmann model is presented to simulate the deformation and motions of a red blood cell （RBC） in a shear flow. The curvatures of the membrane of a static RBC with different chemical potentiM drops calculated by our model agree with those computed by a shooting method very well. Our simulation results show that in a shear flow, biconcave RBC becomes highly flattened and undergoes tank-treading motion. With intrinsically parallel dynamics, this lattice Boltzmann method is expected to find wide applications to both single and multi-vesicles suspension as well as complex open membranes in various fluid flows for a wide range of Reynolds numbers.
基金supported by Excellent Young Teachers Program (3160012261-001)Fund for Basic Research(3160012211104) of Beijing Institute of Technologypartly supported by the National Key Technology R&D Program (2009BAK59B01)
文摘This paper studies red blood cell （RBC） partitioning and blood flux redistribution in microvascular bifurcation by immersed boundary and lattice Boltzmann method. The effects of the initial position of RBC at low Reynolds number regime on the RBC deformation, RBC partitioning, blood flux redistribution and pressure distribution are discussed in detail. It is shown that the blood flux in the daughter branches and the initial position of RBC are important for RBC partitioning. RBC tends to enter the higher-flux-rate branch if the initial position of RBC is near the center of the mother vessel. The RBC may enter the lower-flux-rate branch if it is located near the wall of mother vessel on the lower-flux-rate branch side. Moreover, the blood flux is redistributed when an RBC presents in the daughter branch. Such redistribution is caused by the pressure distribution and reduces the superiority of RBC entering the same branch. The results obtained in the present work may provide a physical insight into the understanding of RBC partitioning and blood flux redistribution in microvascular bifurcation.
基金support from the National Natural Science Foundation of China(Grant Nos.10902098,11372278)the Fundamental Research Funds of the Central Universities(Program No.2010QNA40107)support from the Applied Mathematics Program within the Department of Energys(DOE)Office of Advanced Scientific Computing Research(ASCR)as part of the Collaboratory on Mathematics for Mesoscopic Modeling of Materials(CM4)。
文摘Experimental observations show that a strong magnetic field has a dramatic influence on the sedimentation of RBCs,which motivates us to model the sedimentation of red blood cell(RBC)under strong external magnetic body force.To model the sedimentation of a RBC in a square duct and a circular pipe,a recently developed technique derived from the lattice Boltzmann and the distributed Lagrange multiplier/fictitious domain methods(LBM-DLM/FD)is extended to employ the mesoscopic network model for simulations of the sedimentation of a RBC in flow.The flow is simulated by the LBM with a strong magnetic body force,while the network model is used for modeling RBC deformation.The fluid-RBC interactions are enforced by the Lagrange multiplier.The sedimentation of RBC in a square duct and a circular pipe is simulated,which demonstrates the developed method’s capability to model the sedimentation of RBCs in various flows.Numerical results illustrate that the terminal settling velocity increases incrementally with the exerted body force.The deformation of RBC has a significant effect on the terminal settling velocity due to the change in the frontal area.The larger the exerted force,the smaller the frontal area and the larger the RBC deformation become.Additionally,the wall effect on the motion and deformation of RBC is also investigated.
基金supported by the National Science Foundation of the United States(Nos.DMS-0914788,DMS-1418308)
文摘In this article, a computational model and related methodologies have been tested for simulating the motion of a malaria infected red blood cell （iRBC for short） in Poiseuille flow at low Reynolds numbers. Besides the deformability of the red blood cell membrane, the migration of a neutrally buoyant particle （used to model the malaria parasite inside the membrane） is another factor to determine the iRBC motion. Typically an iRBC oscillates in a Poiseuille flow due to the competition between these two factors. The interaction of an iRBC and several RBCs in a narrow channel shows that, at lower flow speed, the iRBC can be easily pushed toward the wall and stay there to block the channel. But, at higher flow speed, RBCs and iRBC stay in the central region of the channel since their migrations axe dominated by the motion of the RBC membrane.
基金partially supported by the National Natural Science Foundation of China NSFC No.51576033Dalian Innovative Funding of Science and Technology No.2018J12SN076.
文摘One of the important features of the microvessels is with permeable vessels.The hyperpermeablility is especially prounounced due to the fast grow of the microvessel in the tumor tissues.Flow field induced by leakage often presents a different figure compared to that of the health vessel.Non-uniform velocity and pressure distribution are found in the simulation by using Lattice Boltzmann Method combined with Starling law.This non-uniform flow field has significant influence on the mass transport in permeable mocrovessel,such as the motion of red blood cell.Using 2D spring network model to express the red blood cell and immersed boundary method to implement the coupling of fluid and structure,numerical simulations were carried out to study the migration of a red blood cell in a straight permeable channel.The results show that the staying time of red blood cell in the leakage region increases with the intensity of leakage.We also found that the leakage can weaken the lateral migration of the red blood cell from the wall to the channel center,and even tune the migration towards the wall when the leakage is reasonably strong.
