Thrombosis is a common disease among communities and considered as one of the main causes of death in developed countries. Because of major role of blood parameters in the creation and development of this disease and methods of bypass graft to treat it, understanding that how the blood function in vessels is important. In this study, a constant flow of blood to the femoral pulse using the assumption of non-Newtonian fluid and rigid-wall vessels with bypass linked with angles of 30, 45 and 60 degrees and the percentage of stenosis 40, 70 and 100% of the simulation. The results showed that the use of bypass in the vessel containing the stenosis, will reduce average shear stress exerted on the main artery and bypass the angle ° 45 is the best performance of the other angles. Also the effect of the magnetic field and gravity as the wall shear stress was investigated. The results show that an increase in Hartmann number can increase average of pressure, also by applying a magnetic field velocity profile to be flatter and increase the velocity gradient increases shear stress near the wall.

Aterosclerosis and obstructions especially in great and vital arteries cause blood circulation system numerous disorders. Coronary arteries, carotid and femoral as the most important arteries could be affected negatively by aterosclerosis which may result in shock or heart attack. Bypass surgical operation is a significant method to treat clogged arteries nowadays and should be designed as perfect as it would minimize flow turbulence. Numeral simulation techniques are among the most recommended methods to reach this purpose. While most of researchers considered blood as a Newtonian fluid and none has studied magnetic field effect on bypass, we aimed to evaluate blood flow as a non-Newtonian fluid in presence of magnetic field and gravity acceleration in different bypass angels. A model of three-dimensional femoral artery with bypass and rigid wall was assumed. Percentages of blockage was defined by following formula; [(A i -A s )/A i ] in which A i was non-blockage area, and A s was the artery's narrowest part area. Desired geometry was modeled by SolidWorks software then networked in Gambit software. There were three different equations applied including: Equation of the artery in the blockage area, sinusoidal relationship based on Reynolds number and fluid equation of continuity and momentum. Magnetic force of blood flow acted as a resistant tensional force and in presence of magnetic field normal blood flow was observed and subsequently outward viscosity was increased. Magnetic field also caused thickening boundary layer and as velocity gradient increased close to the walls shear stress enhanced. When magnetic field increased and Hartmann number enhanced subsequently there was no observation of negative shear stress. In the bypass entrance a returned flow occurred. By developing the Hartmann number vortex power decreased so that in 10 and 20 Hartmann returned flow was vanished completely. All of hemodynamic parameters and environmental factors that affect them are necessary to improve the efficiency of bypass surgical operations. If the three-dimensional modeling approaches maximally match with the reality they could help the specialists to choose the best location and angel of the bypass and improve the achievement probability significantly.