Simulation numérique du mouvement et de la déformation des ...

AbstractAbstractThe low deformability of neutrophils (white blood cells) and their accumulation inpulmonary capillaries may cause acute respiratory distress syndrome. A computationalfluid dynamic approach using a Volume Of Fluid method is adapted to simulate thebehavior of neutrophils in different confined flow configurations. The white blood cellsare successively represented by four different models : in a first time, the cell is modeledas a Newtonian fluid, characterized by a viscosity and a surface tension. In a secondstep, a non deformable core is added using an immersed boundary method to improverepresentativity of the model. Then, the cytoplasm of the cell is modeled by a viscoelasticfluid. Finally, the effects of an elastic membrane surrounding the cytoplasm are takeninto account so as to separate the motion of the plasma from that of the cell. We discussthe behavior of the cell in three different configurations : an equivalent of the 4-roll milldevice obtained with a suitable arrangement of micro-channels joining at right angle,an isolated contraction and a periodic network in which the cell goes through severalsuccessive contractions. The results shed light on the differences of the cell behaviors obtainedwith the various models. The introduction of a viscoelastic fluid in the cytoplasmdecreases the effective viscosity of the cell and increases its deformability, allowing aneasier entrance in a contraction, whereas the membrane affects the cell shape and decreasesits deformation.Key words : fluid dynamics, numerical simulation, two-phase flow, membrane, viscoelasticity,neutrophils.6