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A two-dimensional computer simulation of blood coagulation was carried out using particle method to investigate thrombus formation due to stagnation of blood flow. Assuming an incompressible and viscous flow, blood flow was calculated with a second-order differential model of the least square moving particle semi-implicit (LSMPS) method. Blood was modeled with normal blood and thrombus particles. A normal blood neighboring the channel wall or the thrombus was changed to a thrombus by the coagulation based on low-shear-rate history. A thrombus particle was connected with neighboring thrombus and channel-wall particles by elastic springs. Our simulation reproduced flow velocity and pressure in a backward facing step flow for Reynolds number of an order of hundred. In a simulation of thrombus formation in a stenosed channel, a thrombus formed in low shear regions; in corner parts neighboring a stenosis and around reattachment points. When a blood coagulation was allowed at higher shear rate, more thrombus was formed to cover entire channel walls except a stenosed part. In an atrium of atriopulmonary connection Fontan circulation, while a layered thrombus was formed on the atrial wall, a ball thrombus was developed in a recirculation region of blood. These results demonstrate the capability of the proposed simulation method to investigated venous thrombus formation that depends on changing blood flow in time and space.

Biomechanics, Computer simulation, Blood flow, Thrombus, Coagulation, Stagnation, Particle Method