Numerical Studies On The Motion And Deformation Of A Red Blood Cell In Shear And Tube Flow

In the human body,red blood cells(RBC)accounts for about 99% of all blood cells in number,so that they determine properties of the whole blood,to some extent.The motion and deformation of a RBC affect behaviors of blood flow,such as the formation of thrombus caused by the abnormal motion and deformation of RBCs;RBC's abnormalities in motion and deformation are also accompanied by the occurrence and development of diseases,such as malaria,sickle-shaped RBC anaemia,etc.Therefore,it is significant to study the motion and deformation of RBC for understanding blood flow and some diseases.Moreover,it is also required to probe the motion and deformation of RBCs in the application of artificial blood and artificial blood pumps.As we know,blood starts from the heart,flows through arteries,capillaries,veins,and then back to the heart in a circulation period.The blood vessels' diameters change from a few centimeters to several micrometers.In large blood vessels(several centimeters),the motion of a RBC can be seen approximately as the motion in shear flow,while in the narrow blood vessels(several micrometers),it should be seen as the motion in tube flow because the RBC is compared with the vessel in diameter.Therefore,this dissertation mainly numerically studies the motion and deformation of a RBC in both shear flow and tube flow.We used Smoothed Dissipative Particle Dynamics(SDPD)to model the flow of fluid inside and outside a RBC.Its membrane was modeled as a triangular network to describe its deformation,including shear deformation,bending deformation,incompressibility of the surface area and the cell impermeability.Immersed Boundary Method(IBM)was used to handle the interaction between cell and fluid.Based on these models,we analyzed the motion and deformation of a single RBC in shear flow and tube flow,respectively.The simulation results reproduced three typical modes in the motion and deformation of RBC in shear flow: tank-treading at the steady state,swinging at the transitional state,and tumbling at the unstable state.Two modes in tube flow were also presented: parachute shape in the symmetric state and slipper shape in the asymmetrical state.