Seyedeh Sarah Salehi - Mechanical Engineering Department Sharif University of Technology Tehran, Iran.
Bahar Firoozabadi - Mechanical Engineering Department Sharif University of Technology Tehran, Iran.
Mohamad Said Saidi - Mechanical Engineering Department Sharif University of Technology Tehran, Iran.

The brain is one of the vital organs in the body.The main cerebral distribution center of blood flow in the brain is the circle of Willis (CoW). In more than 50% ofhealthy brains and in more than 80% of dysfunctional ones, at least one artery of the circle of Willis is absent or underdeveloped . These variations reduce the collateral flowavailability and increase the risk of stroke and transient ischemic attack in patients with atherosclerosis. Thus it isessential to simulate the circle of Willis and investigate the effects of stenosis. In this work the systemic arteries along with the circle ofWillis are simulated using the finite volume method andone- dimensional equations of conservation of mass and momentum. The structured tree is considered as the outletboundary condition. The results show that blood flow rate, pressure and velocity through vessels are consistent with previous results. Meanwhile, the internal Carotid artery (ICA) stenosis is simulated and the collateral capacity of the circle of Willis is shown. As the area of the ICA decreases, the velocity of blood through communicating arteries is increased but this ability is reliable to a special extent ofarea reduction in the ICA.

circle of Willis, stenosis, structured tree, systemic circulation