TWO-DIMENSIONAL NUMERICAL SIMULATION FOR THE EFFECT OF CAPSULE ELASTICITY ON ITS BEHAVIOR NEAR A PLATE IN A FLUID UNDER AN INCLINED CENTRIFUGAL FORCE FIELD
Suguru Miyauchi1, Toshiyuki Hayase1, Luca Brandt2, Fredrik Lundell2, Shervin Bagheri2
1Institute of Fluid Science, Tohoku University, Japan;
2KTH Royal Institute of Technology, Sweden
Blood flow in microcirculation plays an important role in mass transfer, such as the supply of nutrients and the collection of waste. In microcirculation, diameters of blood vessels are smaller than the size of an erythrocyte, and it is considered that complex interactions occur between the erythrocytes and the endothelial cells on the blood vessels. For elucidation of the interaction, frictional characteristics of erythrocytes on material-coated and endothelia-cultured plates were measured by an inclined centrifuge microscope. In our previous study, the frictional characteristics for the material-coated plates were properly explained by a numerical simulation mimicking the experiment. The study assumed a rigid erythrocyte model with a flat bottom surface, but the validity of this assumption has not yet been confirmed. It should, therefore, be clarified how a real erythrocyte deforms and behaves in the inclined centrifuge microscope. As the fundamental consideration, the purpose of this study was to clarify the behavior of an initially circular elastic capsule near a flat plate in a fluid under the effect of inclined centrifugal force by two-dimensional fluid-structure interaction analysis. An immersed boundary method was employed to treat the interaction between the fluid and membrane. Numerical results showed that the bottom side of the capsule becomes flat with an attack angle in the equilibrium state. These results support the assumption used in the previous study. Rotational motion, or tank-treading motion, was observed for the capsule. The present results also clarified the effects of elasticity on the translational and rotational velocities and the distance from the plate for the capsule.